Ensure an MR never has negative approvals left

Closes #959.

See merge request !708

Port policies to EE

Ports https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5796 to EE, maintaining EE-only differences.

Assuming this all works, I think we should put this block in CE as well just to prevent future conflicts:

```ruby
    # EE-only
    if defined?(License) && License.block_changes?
      cannot! :create_issue
      cannot! :create_merge_request
      cannot! :push_code
      cannot! :push_code_to_protected_branches
    end
```

In addition to cherry-picking the gitlab-org/gitlab-ce@e71cd7a300017cf85e16de3b1c68fdb25c3a4b4d commit, which is the merge of the Policy refactor itself, I had to cherry-pick gitlab-org/gitlab-ce@6686084c6502f10fd7e6b8963ab52526cb6831bf because it added the `Project#has_wiki?` method that specs depended on.

See merge request !702

Remove (unreleased) for 8.11.3



See merge request !703

Refactor ability.rb into Policies

Factors out `ability.rb` into a new abstraction - the "policy" (stored in `app/policies`). A policy is a class named `#{class_name}Policy` (looked up automatically as needed) that implements `rules` as follows:

``` ruby
class ThingPolicy < BasePolicy
  def rules
    @user # this is a user to determine abilities for, optionally nil in the anonymous case
    @subject # this is the subject of the ability, guaranteed to be an instance of `Thing`
    can! :some_ability # grant the :some_ability permission
    cannot! :some_ability # ensure that :some_ability is not allowed. this overrides any `can!` that is called before or after
    delegate! @subject.other_thing # merge the abilities (can!) and prohibitions (cannot!) from `@subject.other_thing`
    can? :some_ability # test whether, so far, :some_ability is allowed
  end

  def anonymous_rules
    # optional. if not implemented `rules` is called where `@user` is nil. otherwise this method is called when `@user` is nil.
  end
end
```

See merge request !5796

Hide group control nav if no options present

Taken from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5155

See merge request !701

Taken from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5155

Fix typo: `bassis` -> `basis`



See merge request !698

CE upstream



See merge request !697

Add title to CI lint page

![Screen_Shot_2016-08-30_at_10.56.23](/uploads/651ce9e303b65854e96b18d301dcf1a3/Screen_Shot_2016-08-30_at_10.56.23.png)![Screen_Shot_2016-08-30_at_10.56.37](/uploads/77cb710971c4b84e659cbf9bbe13a1cb/Screen_Shot_2016-08-30_at_10.56.37.png)

See merge request !6100

Mention that the `:id` of a project can also be `NAMESPACE/PROJECT_NAME`

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/18936

See merge request !6102

[ci skip]

Ensure we update dropdown label after input has been added

Backport changes from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/687

See merge request !5999

Change logo animation to CSS

## What does this MR do?
Converts the tanuki logo animation from javascript to CSS. You can now animate the tanuki svg logo by adding the CSS Class `animate`to it.

## Are there points in the code the reviewer needs to double check?
Just need to double check for browser compatibility

## Why was this MR needed?

*  Using CSS for simple animations is a best practice (Optimizes DOM, uses GPU to do animation rather than CPU)
*  Happy DOM 🎈 

## What are the relevant issue numbers?
Closes #20607 

## Screenshots (if relevant)
Before DOM
![8BrOJAqT4U](/uploads/705a3c7b53c45d32d435cafecfc958bd/8BrOJAqT4U.gif)

After DOM
![Screen_Shot_2016-08-03_at_10.30.08_PM](/uploads/e82d9b63501def4dc4e67a5659863680/Screen_Shot_2016-08-03_at_10.30.08_PM.png)

Before
![JnEgliIIVO](/uploads/39aaec48fd3e193f20cf455371ea2d13/JnEgliIIVO.gif)

After (Basically the same, hard to tell in my gif though because it was hard to get the timings right on the recording)
![fvLeXxmp3U](/uploads/058cf15fffed4be549af2e963eca4412/fvLeXxmp3U.gif)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5655

Remove unused mixins

## What does this MR do?
Remove unused mixins

## Are there points in the code the reviewer needs to double check?
None

## Why was this MR needed?
Reduces unused css

## Screenshots (if relevant)
Before:
```
$git grep 'btn-big' -- '*.scss'
app/assets/stylesheets/framework/mixins.scss:107:@mixin btn-big {

$git grep 'input-big' -- '*.scss'
app/assets/stylesheets/framework/mixins.scss:97:@mixin input-big {

$git grep 'solid-shade' -- '*.scss'
app/assets/stylesheets/framework/mixins.scss:45:@mixin solid-shade {

$git grep 'shade' -- '*.scss'
app/assets/stylesheets/framework/mixins.scss:41:@mixin shade {
app/assets/stylesheets/framework/mixins.scss:45:@mixin solid-shade {

$git grep 'linear-gradient' -- '*.scss'
app/assets/stylesheets/framework/buttons.scss:310:  background: linear-gradient(180deg, $white-light 25%, $gray-light 100%);
app/assets/stylesheets/framework/mixins.scss:20:@mixin linear-gradient($from, $to) {
app/assets/stylesheets/framework/mixins.scss:22:  background-image: -webkit-linear-gradient($from, $to);
app/assets/stylesheets/framework/mixins.scss:23:  background-image: -moz-linear-gradient($from, $to);
app/assets/stylesheets/framework/mixins.scss:24:  background-image: -ms-linear-gradient($from, $to);
app/assets/stylesheets/framework/mixins.scss:25:  background-image: -o-linear-gradient($from, $to);
app/assets/stylesheets/framework/nav.scss:11:  background: -webkit-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/framework/nav.scss:12:  background: -o-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/framework/nav.scss:13:  background: -moz-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/framework/nav.scss:14:  background: linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/pages/diff.scss:167:        background-image: linear-gradient(45deg, #e5e5e5 25%, transparent 25%, transparent 75%, #e5e5e5 75%, #e5e5e5 100%),
app/assets/stylesheets/pages/diff.scss:168:        linear-gradient(45deg, #e5e5e5 25%, transparent 25%, transparent 75%, #e5e5e5 75%, #e5e5e5 100%);

$git grep 'border-radius-left' -- '*.scss'
app/assets/stylesheets/framework/mixins.scss:12:@mixin border-radius-left($radius) {

$git grep 'border-radius-right' -- '*.scss'
app/assets/stylesheets/framework/mixins.scss:16:@mixin border-radius-right($radius) {
```

After:
```
$git grep 'btn-big' -- '*.scss'
(nothing)

$git grep 'input-big' -- '*.scss'
(nothing)

$git grep 'solid-shade' -- '*.scss'
(nothing)

$git grep 'shade' -- '*.scss'
(nothing)

$git grep 'linear-gradient' -- '*.scss'
app/assets/stylesheets/framework/buttons.scss:310:  background: linear-gradient(180deg, $white-light 25%, $gray-light 100%);
app/assets/stylesheets/framework/nav.scss:11:  background: -webkit-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/framework/nav.scss:12:  background: -o-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/framework/nav.scss:13:  background: -moz-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/framework/nav.scss:14:  background: linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
app/assets/stylesheets/pages/diff.scss:167:        background-image: linear-gradient(45deg, #e5e5e5 25%, transparent 25%, transparent 75%, #e5e5e5 75%, #e5e5e5 100%),
app/assets/stylesheets/pages/diff.scss:168:        linear-gradient(45deg, #e5e5e5 25%, transparent 25%, transparent 75%, #e5e5e5 75%, #e5e5e5 100%);

$git grep 'border-radius-left' -- '*.scss'
(nothing)

$git grep 'border-radius-right' -- '*.scss'
(nothing)
```

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #21559

See merge request !6092

Keep committing ... spinner when conflict resolved

## What does this MR do?

When a conflict is resolved successfully, keep the 'committing ...' spinner until the new page loads rather than showing the standard button again, which is misleading. The old behaviour looks like this:

![Resolve_merge_conflict](/uploads/8e0efec0bb4b1358d4dd3353ea1dc57b/Resolve_merge_conflict.gif)

I don't think this needs a CHANGELOG entry as it's pretty minor.

See merge request !5892

Merge branch '21285-new-merge-request-source-and-target-branch-fields-filters-both-source-and-target-list' into 'master'

Fixed issue where filtering one dropdown will filter another on the page

## What does this MR do?

Moved `.option-hidden` to exist only in `SELECTABLE_CLASSES` as `NON_SELECTABLE_CLASSES` is used to re-show previously hidden elements.

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

## What are the relevant issue numbers?

Closes #21285.

## Screenshots (if relevant)

![2016-08-24_15.59.16](/uploads/8282bd6507d10de61097956a57bd63cc/2016-08-24_15.59.16.gif)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
Closes #21285

See merge request !5985

Add body as data-container on pipeline graph tooltip

## What does this MR do?
Fixed data tooltip getting cut off

## What are the relevant issue numbers?
Closes #21070 

## Screenshots (if relevant)
![Screen_Shot_2016-08-23_at_8.45.42_AM](/uploads/87f072cfc2fdeced6161db6bec46320a/Screen_Shot_2016-08-23_at_8.45.42_AM.png)

See merge request !5955

Removes leading space from hover state in graph links

#### What are the relevant issue numbers?
Closes #21123 

#### Screenshots (if relevant)
![Screen_Shot_2016-08-24_at_8.35.15_AM](/uploads/2dc583391f87c6d0a67f0535967c637f/Screen_Shot_2016-08-24_at_8.35.15_AM.png)

See merge request !5980

Clarify steps when changing a document's location

Clarify the steps needed to change a document's location so issues like
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6024
don't occur.

See merge request !6070

[ci skip]

Make push events have equal vertical spacing.

## What does this MR do?

Evens out the vertical space between lines in push events.

## Are there points in the code the reviewer needs to double check?

Not afaik. 

## Why was this MR needed?

UI consistency.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/19517

## Screenshots (if relevant)

Before: 
![Screen_Shot_2016-08-26_at_5.23.33_PM](/uploads/78e7a89912ec504d598f9bfec2a83eea/Screen_Shot_2016-08-26_at_5.23.33_PM.png)
After: 
![Screen_Shot_2016-08-26_at_5.23.16_PM](/uploads/3fa3e0902ef76b1e9c82e052842cd0ee/Screen_Shot_2016-08-26_at_5.23.16_PM.png)




## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

cc: @winniehell

See merge request !6055

First pass for community issue templates

## What does this MR do?

Includes community issue templates for Bugs and Feature Proposals.

In combination with a default Issue description template in the Project settings, we can advise the best places to find help and what is suitable to be posted to the CE issue tracker.

## Are there points in the code the reviewer needs to double check?

Verify that the templates are good

## Why was this MR needed?

To bring uniformity to the issues posted to the CE issue tracker

## What are the relevant issue numbers?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

N/A

See merge request !5954

Fix branches page dropdown sort alignment

## What does this MR do?
Makes the dropdown sort top aligned with the other elements beside it

## Are there points in the code the reviewer needs to double check?
Shouldn't be

## Why was this MR needed?
Improves the UI

## What are the relevant issue numbers?
Closes #20837 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-11_at_10.08.56_AM](/uploads/d446c65276d856f6257921c0e662d110/Screen_Shot_2016-08-11_at_10.08.56_AM.png)
![Screen_Shot_2016-08-11_at_10.08.55_AM__2_](/uploads/015f0ac263281275405b127cd19718b4/Screen_Shot_2016-08-11_at_10.08.55_AM__2_.png)

After:
![Screen_Shot_2016-08-11_at_10.15.35_AM](/uploads/73a231d4e4d474b3cfbc6944ddd4f0e9/Screen_Shot_2016-08-11_at_10.15.35_AM.png)
![Screen_Shot_2016-08-11_at_10.08.36_AM__2_](/uploads/c5cda7911258766c02554f68ebd4bf82/Screen_Shot_2016-08-11_at_10.08.36_AM__2_.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5777

Fix due date example in slash commands documentation

## What does this MR do?

Fixes due data example in documentation for slash commands.

## Screenshots

Before:

![due_date_slash_commands_before](/uploads/63484bfcad6605e7caf2a98f39ae65d0/due_date_slash_commands_before.png)

After:

![slash_commands_brackets](/uploads/5a75563eb797b4d694c6e4eca946e17a/slash_commands_brackets.png)

See merge request !5931

Prevent .form-actions from leaking out of the container (originally by @pavelloz)

{+addition+} **This MR was originally by @pavelloz in !4889, the MR was inactive for 2 months and is a ~P3, I have credited @pavelloz in the `CHANGELOG`. The description below is also copied from that MR.**

## What does this MR do?
Fixes div width leaking outside  

## Are there points in the code the reviewer needs to double check?
Any place where it might been needed when introduced couple months ago.

## Why was this MR needed?

## What are the relevant issue numbers?
{+addition+}
Closes #18731.
## Screenshots (if relevant)
Before
![image](/uploads/f7bfb18a5949e95ab876f8c140ef1c91/image.png)
![image](/uploads/81d4f99ba3334f46f04bd078eefa2548/image.png)


After
![image](/uploads/f34b1e2bf4d8849275c206e66ccb8398/image.png)
![image](/uploads/2664adfcf00ca6831629a8fdab68f6f6/image.png)


## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

cc @jschatz1

See merge request !6075