Document environments and deployments

## What does this MR do?

Adds an introduction to environments and deployments and tweaks the `environments` entry in `.gitlab-ci.yml` documentation.

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

## Why was this MR needed?

## What are the relevant issue numbers?

Closes #18683.

## Screenshots (if relevant)

![image](/uploads/1e3355c543abaf7b358f3c37596b1f0b/image.png)

![image](/uploads/58a51505674bcf605039db46833a8ae6/image.png)

/cc @ayufan @axil 

See merge request !4725

Remove Duplicated keys adding UNIQUE index to fingerprint

See merge request !4787

Avoid autoload issue such as 'Mail::Parsers::AddressStruct'

This is mostly a shot in the dark but at least it shouldn't break anything.

Fixes #18810.

See merge request !4793

Limit push email diff size

Restrict the size of diffs in push emails to 30 lines / 150 KB (whichever is smaller),
following https://gitlab.com/gitlab-org/gitlab_git/merge_requests/85.

Emails on push can get very large if they contain a lot of files that sneak under the single-file limit.

https://gitlab.com/gitlab-org/gitlab-ee/issues/490

See merge request !4566

Move part of admin area navigation from tabs into settings dropdown

Partly fix https://gitlab.com/gitlab-org/gitlab-ce/issues/18799 

See merge request !4796

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Grammar tweaks

## What does this MR do?

* Updates grammar in recent CI documentation.

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

## Why was this MR needed?

Because grammar.

## What are the relevant issue numbers?

Needed because of !4200 and !4201.

## Screenshots (if relevant)


See merge request !4772

Add documentation styleguide  on configuration settings

See merge request !4794

[ci skip]

By eager-loading the Mail gem in the Sidekiq initializer.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixed a couple of errors on import/export spotted in production

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/18828 and https://gitlab.com/gitlab-org/gitlab-ce/issues/18829

A couple of tiny bugs spotted after deploying in prod

See merge request !4782

Fix RangeError exceptions when referring to issues or merge requests outside of max database values

When using #XYZ in Markdown text, if XYZ exceeds the maximum value of a signed 32-bit integer, we get an exception when the Markdown render attempts to run `where(iids: XYZ)`. Introduce a method that will throw out out-of-bounds values.
    
Closes #18777

See merge request !4777

When using #XYZ in Markdown text, if XYZ exceeds the maximum value of a signed 32-bit integer, we
get an exception when the Markdown render attempts to run `where(iids: XYZ)`. Introduce a method
that will throw out out-of-bounds values.

Closes #18777

Display Star and Fork on mobile, fix #18537.

## What does this MR do?

Displays the Star and Fork buttons on mobile devices.

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

Nope.

## Why was this MR needed?

I wanted to star and/or fork projects while on my phone, I couldn't do that before.

## What are the relevant issue numbers?

#18537 

## Screenshots (if relevant)

![Screen_Shot_2016-06-16_at_11.41.24_AM](/uploads/053ac0c1b39a7b1b30fffb0a8d43cffb/Screen_Shot_2016-06-16_at_11.41.24_AM.png)

cc: @jschatz1 

See merge request !4714

Add merge request data to the progress information on Milestones pages.

## What does this MR do?

Adds data about merge requests to the Milestone show view. It previously only showed something like `3 issues: 2 open and 1 closed 20% complete`, now it shows `3 issues: 2 open and 1 closed 2 merge requests: 2 open and 0 merged 20% complete`.

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

I don't think so.

## Why was this MR needed?

The milestone progress % didn't accurately reflect the open/merged MRs.

## What are the relevant issue numbers?

Fixes #13980

## Screenshots (if relevant)

Before:

![Screen_Shot_2016-06-16_at_2.12.57_PM](/uploads/99a044ea918b23fe93cef3305c21086e/Screen_Shot_2016-06-16_at_2.12.57_PM.png)

After:

![Screen_Shot_2016-06-16_at_2.12.38_PM](/uploads/be17e723b9c9bbe33099d1f0e94192d0/Screen_Shot_2016-06-16_at_2.12.38_PM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [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 !4719

Fix margin & padding on activity btn

## What does this MR do?
Fixes alignment of activity btn

## What are the relevant issue numbers?
Closes #18762 

## Screenshots (if relevant)
![Screen_Shot_2016-06-17_at_9.29.06_AM](/uploads/4ab9fb33d450dda72811a5ce2570b8c7/Screen_Shot_2016-06-17_at_9.29.06_AM.png)


See merge request !4750

Fixed alignment of buttons in note forms

## What does this MR do?

Due to a CSS change on some buttons, the alignment of the save button on the note form went off. Also, it made no sense to have `.btn-grouped` as the button wasn't in a group.

## Screenshots (if relevant)

![Screen_Shot_2016-06-17_at_11.43.33](/uploads/5d9037a48ff6179fc906bdf0c6d5ff47/Screen_Shot_2016-06-17_at_11.43.33.png)

![Screen_Shot_2016-06-17_at_11.43.43](/uploads/8b130a25e8f73e79578d38f5f7aff4fb/Screen_Shot_2016-06-17_at_11.43.43.png)


See merge request !4740

Move admin->runners tab as subnav of overview tab

cc @annabeldunstone 

See merge request !4716

Fixed tooltip placement on edit tags button

## What does this MR do?

Moves the placement of the tooltip to the body so not to affect the movement of the button.

## Screenshots (if relevant)

Old:

![tooltip-old](/uploads/9ecb9bb919578881994698cd8b1d1826/tooltip-old.gif)

New:

![tooltip-new](/uploads/66f90cf95c2ee4001bfa3c65b9de8c05/tooltip-new.gif)


See merge request !4737

Fixed size of buttons in branches list

## What does this MR do?

The buttons on the branch list were using `btn-xs` this MR removes that so the buttons are a normal size to match https://gitlab.com/gitlab-org/gitlab-ce/tags

## What are the relevant issue numbers?

#18677 

## Screenshots (if relevant)

![Screen_Shot_2016-06-17_at_10.38.31](/uploads/19fc173e3f549a84bb14517613403792/Screen_Shot_2016-06-17_at_10.38.31.png)

See merge request !4735

Aligns create merge request button vertically

## What does this MR do?

Based on https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4644#note_12507178 I have vertically aligned the button correctly.

## Screenshots (if relevant)

Here is my awesome screenshot to show it is centered vertically 

![Screen_Shot_2016-06-17_at_10.17.19](/uploads/e7bf5bcc5b254ed4db376c16460d79a5/Screen_Shot_2016-06-17_at_10.17.19.png)

See merge request !4733

Fixes item icon state when for issues that have the same labels assigned

## What does this MR do?
Previously if all issues had the same labels the dropdown was showing the labels with indeterminate stated which is wrong. This MR fixes that and shows the correct state.

## What are the relevant issue numbers?
Fixes #18714

## Screenshots (if relevant)

**Before**

![label-before](/uploads/c65aa051e773dfea898a0d19767d6ade/label-before.gif)

**After**

![label](/uploads/73fd657d104d1081e189e0a9547d483b/label.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)
- [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 !4721

Hide tooltip manually

## What does this MR do?
Fixes an issue with tooltips not dissapearing  on Firefox after toggling label priority

## What are the relevant issue numbers?
Closes #18707

## Screenshots (if relevant)

**Test on Firefox**

![label-firefox](/uploads/09ed05f81b9861d666e5d9ad805fb501/label-firefox.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
  - [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 !4715

Fix bug in `WikiLinkFilter`.

Closes #18819 

- [ ]  #18819 Wiki link filter exception
    - [x]  Make sure [build](https://gitlab.com/gitlab-org/gitlab-ce/commit/6d169d36cabda783116bcb8e2e6f73254566a670/builds) passes
    - [ ]  Wait for merge
    - [ ]  Pick into 8.9

See merge request !4775

1. An exception would be raised if the filter was called with an invalid
   URI. Mainly because we weren't catching the `Addressable` exception.

2. This commit fixes it and adds a spec for the filter.

Ci scala example

## What does this MR do?

Add a scala CI example.

## Why was this MR needed?

Supersedes https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2984

See merge request !4774

Implement custom notification level options

![Screen_Shot_2016-06-17_at_15.31.43](/uploads/3fc47d2f461b3e8b67bb8acaa304cf99/Screen_Shot_2016-06-17_at_15.31.43.png)

![Screenshot_from_2016-06-15_10-52-27](/uploads/88dbdd21d97e80ee772fe08fa0c9b393/Screenshot_from_2016-06-15_10-52-27.png)

part of #12758 

See merge request !4389

Ensure that group owner cannot request access to a project of their group

## What does this MR do?

It fixes two things:

- 91ad995d69e1a0f8991fd896f1d9febc109273fe Ensure that group owner cannot request access to a project of their group
- ec3ff061148d556757e7cd486cdc6083d77acf34 Ensure group/project owners can see their members' access_level (see the commit message for details)

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

Not really, these are pretty simple fixes.

## Why was this MR needed?

Because there was an issue created!

## What are the relevant issue numbers?

Fixes #18717.

## Does this MR meet the acceptance criteria?

- [x] CHANGELOG is not needed since the bug is only present in a 8.9 RC
- [x] 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)

See merge request !4729

# Conflicts:
#	app/controllers/projects/todos_controller.rb

Avoid that GitHub import fails when retrieving Webhooks for non GitHub admins

Closes #18729 

See merge request !4723

[ci skip]