Revert "Optimistic locking for Issue and Merge Requests"

The migration to add `lock_version` in !5146 to every issue and merge request takes too long on GitLab.com since it has to add a default value of 0 to every row. Unfortunately, Rails 4.2 doesn't work properly if the value is left as `nil`; anything using optimistic locking cannot be edited. 

This bug was fixed in Rails 5.0 via this commit: https://github.com/rails/rails/commit/13772bfa49325a8dc26410d2dcb555665a320f92. I suggest we revert this change for now, and when we upgrade to Rails 5.0 we can reintroduce this feature.

See merge request !5245

Update rubocop to 0.41.2

Adds a couple of cops to the TODO files, but I wanted [a specific cop](https://github.com/bbatsov/rubocop/pull/3135/files) which just had about 65 offences, so Ill do that later.

See merge request !4999

Disable PostgreSQL statement timeout during migrations

Long-running migrations may take more than the timeout allowed by the database. Disable the session's statement timeout to ensure migrations don't get killed prematurely.

See merge request !5263

Fix issues last update timestamp not preserved after importing a project

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19689 and https://gitlab.com/gitlab-org/gitlab-ce/issues/19792 (similar, but not the same)

Now `updated_at` should be the time from the original project.

See merge request !5253

Reduce padding on collapsed diff message

## What does this MR do?

Reduce the padding on the collapsed diff message so it takes up less space.

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

## Why was this MR needed?

Collapsed diffs took up too much space before.

## Screenshots (if relevant)

Before:

![image](/uploads/62c6fe19439bc3bc91bde83df72e7004/image.png)

After:

![image](/uploads/ec89230065c37fc4022d949d1233a90d/image.png)

## 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~~
  - [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 !5256

Changed collapsed assignee tooltip to users name

## What does this MR do?

- Changes the collapsed assignee tooltip the users name rather than the username
- Updates the tooltip after updating the assignee

## What are the relevant issue numbers?

Closes #19280, #19281

## Screenshots (if relevant)

![Screen_Shot_2016-06-28_at_17.55.52](/uploads/e6ccc1703f59966c978e731a841aabdc/Screen_Shot_2016-06-28_at_17.55.52.png)

See merge request !4976

navbar_icon was renamed to custom_icon

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4909 it's still using `navbar_icon` but now it's renamed to `custom_icon` in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5156

/cc @iamphill @smcgivern @annabeldunstone 

See merge request !5265

Address UI feedback for admin area

## What does this MR do?
Addresses @dzaporozhets's feedback for !4424

## Why was this MR needed?
!4424 was merged with some design issues which affected other areas of the app and broke consistency. This MR fixes that.

## What are the relevant issue numbers?
#3946 

## 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
  - [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)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5190

Update permissons links to new page

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5210 updated the location in the docs, but we link to this page a bunch in the app too.

See merge request !5247

https://gitlab.com/gitlab-org/gitlab-ce/commit/c57471ddb456c9640f6d77128e1fc56c7a5b35b2

navbar_icon was used in:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4909

Refresh branch cache after `git gc`

As discussed in !5160, we should refresh the branch name list after expiring to make sure we are in a good state and that we do not affect view performance (as much).


See merge request !5235

GL dropdowns in issuable form

## What does this MR do?

Changed all the issuable dropdown menus over to user GL dropdowns. This brings the dropdowns to be inline with the issuable filter dropdowns and allows for labels to be created whilst creating/editing an issuable.

## What are the relevant issue numbers?

Closes #12574 

## Screenshots (if relevant)


See merge request !4970

Projects blank state

## What does this MR do?

Adds a designed blank state to dashboard/projects

## What are the relevant issue numbers?

Part of #18519 

## Screenshots (if relevant)

![Screen_Shot_2016-06-24_at_17.14.46](/uploads/593ea1c5efa2310a0f94b2d56d94cf3c/Screen_Shot_2016-06-24_at_17.14.46.png)

See merge request !4909

Updated compare dropdowns

## What does this MR do?

Removes jQuery autocomplete from compare fields and replaces with GitLabs dropdowns.

## What are the relevant issue numbers?

Closes #18891 

## Screenshots (if relevant)

![Screen_Shot_2016-06-24_at_14.24.34](/uploads/f34370390183429f604fc48645390f2f/Screen_Shot_2016-06-24_at_14.24.34.png)

See merge request !4895

Long-running migrations may take more than the timeout allowed by
the database. Disable the session's statement timeout to ensure
migrations don't get killed prematurely.

Pipeline row improvements

## What does this MR do?
Makes minor pipeline row improvements:
* Add margin between labels
* Remove underline hover style on status button
* Add margin between buttons if both retry and cancel are present

## What are the relevant issue numbers?
Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/18920

## Screenshots (if relevant)
![Screen_Shot_2016-07-14_at_12.31.54_PM](/uploads/ae88651cb240ea90a0be58ab0ed65805/Screen_Shot_2016-07-14_at_12.31.54_PM.png)

See merge request !5258

Fix import_data being saved as a result of an invalid import_url

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19479

Seem that in all cases the `import_url` was an empty string. The `import_url` is now validated correctly and no longer creates the `import_data`even if it fails validation. <= Should cover cases 1, 3, and 4 of https://gitlab.com/gitlab-org/gitlab-ce/issues/19479#note_13005276

Also, it now rescues from all exceptions when importing from a URL, so we make sure the `import_status` is failed after that. Covers case 2 of https://gitlab.com/gitlab-org/gitlab-ce/issues/19479#note_13005276

See merge request !5206

Cleanup feature proposal template

## What does this MR do?

Changes the recommended template for feature proposals.

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

## Why was this MR needed?

I've been using the template for a while, and find that putting so many words into the h2 makes me think there's actual content there, until I realize I'm just reading the template text (again). I think we can get away with just putting `Description` as the header, and putting the suggested content for that section as plain text below for someone to replace.

## What are the relevant issue numbers?

## Screenshots (if relevant)

![image](/uploads/20a99c98a12aad84c1a7ec020f365b2f/image.png)

/cc @JobV 

See merge request !5240

Use default cursor for table header of project files

## What does this MR do?

Use default cursor for table header of project files.

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

Nope.

## Why was this MR needed?

The table header had a pointer cursor even though it was not clickable.

## What are the relevant issue numbers?

fixes #19612


See merge request !5165

Added shortcut to focus filters

## What does this MR do?

Adds shortcut `f` to focus filter inputs.

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

Is this a valid implementation?

Please check [this comment below](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4570#note_12359978)!

## Why was this MR needed?

Keyboard ninja UX ⚔ 

## What are the relevant issue numbers?

Closes #18120.

## Screenshots (if relevant)

![Screen_Shot_2016-06-09_at_18.34.56](/uploads/d4cfb6ec340c118f5227be3f16ffbed1/Screen_Shot_2016-06-09_at_18.34.56.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
  - [ ] 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)

See merge request !4763