Add es6 gem

## What does this MR do?
Add ES6 to ES5 compiling via Babel and the sprockets es6 gem.

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

## Why was this MR needed?
So we can write ES6

## What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/20098

## Screenshots (if relevant)
![Screen_Shot_2016-07-25_at_10.56.02_AM](/uploads/04ceeedb8235fd3a7601bc4bece313a8/Screen_Shot_2016-07-25_at_10.56.02_AM.png)

![Screen_Shot_2016-07-25_at_10.55.54_AM](/uploads/163c46a3d878924ab1717fccca468003/Screen_Shot_2016-07-25_at_10.55.54_AM.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)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] 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)

See merge request !5473

Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix backup restore

## What does this MR do?

This MR fixes the backup restore task.

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

Whether the mode 0277 makes sense. (Group SUID + group/user read/write permissions)

## Why was this MR needed?

86359ec8 broke this, and it was not caught by any specs. Users would see:

```
Restoring repositories ...
rake aborted!
NameError: undefined local variable or method `repos_path' for #<Backup::Repository:0x00000007cea1d8>
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/repository.rb:59:in `restore'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:79:in `block (4 levels) in <top (required)>'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:54:in `block (3 levels) in <top (required)>'
Tasks: TOP => gitlab:backup:repo:restore
(See full trace by running task with --trace)
```

## What are the relevant issue numbers?

#20188

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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 !5459

Instrument Nokogiri parsing methods

## What does this MR do?

This MR instruments the various parsing methods of Nokogiri.

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

No.

## Why was this MR needed?

This allows us to see how much time is spent in Nokogiri.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] ~~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)
- [ ] 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 !5470

This allows us to see how much time is being spent in just parsing
HTML/XML documents.

Set permissions of backup dir to g+s

Closes #20188

Use project ID in repository cache to prevent stale data from persisting across projects

See merge request !5460

Add iid to MR API response

## What does this MR do?

Adds `iid` parameter to the MR API docs. 

## Why was this MR needed?

It is missing.

## What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/19578

## Does this MR meet the acceptance criteria?

- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)


See merge request !5468

We have a number of bugs caused by cache keys not being flushed
properly during deletion of a project. Add the project ID to ensure
this never happens.

Closes #20027

Users can filter branches by name on project branches page

This MR aims to solve #18674 by adding the possibility to filter project branches by name

![Screen_Shot_2016-07-07_at_17.21.25](/uploads/b674765d2b1cb8a121c2101715a4568b/Screen_Shot_2016-07-07_at_17.21.25.png)

See merge request !5144

Remove magic comments from Ruby files

## What does this MR do?

Remove magic comments (`# encoding: UTF-8`) from Ruby files.

## Why was this MR needed?

Since Ruby 2, UTF-8 is the default encoding and those comments are no longer necessary.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5163#note_13134307

cc @rymai 

See merge request !5456

Make fork counter always clickable

## What does this MR do?

Make the fork counter on project pages clickable for people who forked the project.

## Why was this MR needed?

The fork counter was not clickable.

## What are the relevant issue numbers?

fixes #20205


See merge request !5463

See !5454.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix Error 500 when creating Wiki pages with hyphens or spaces

- Closes gitlab-com/support-forum#874
- Closes #20209 

See merge request !5444

1. So we can build the markdown preview URL for it.

2. We can't skip the slug in this case, because the slug is used to
construct relative markdown URLs.

3. Add rspec feature tests to cover creating wiki pages with
   spaces/hyphens in the name.

4. Add rspec feature tests for markdown preview URL rewriting, which was
   only covered by unit tests up to this point.

ES6ify all the things!



See merge request !5464

Revert "Merge branch '17073-tagscontroller-index-is-terrible-response-time-goes-up-to-5-…"

## What does this MR do?

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

## Why was this MR needed?

## What are the relevant issue numbers?

## Screenshots (if relevant)

## 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)

See merge request !5461

This reverts merge request !5375

Closes gitlab-com/support-forum#874

Add links to the real markdown.md file for all GFM examples

## What does this MR do?

Add links to the real markdown.md file for all GFM examples since they will not render correctly on docs.gitlab.com.

We already have a note https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5440, but better be explicit.

See merge request !5458

Certain reverse proxies can send invalid IP addresses in the X-Forwarded-For header
For example, Apache can send (null).

Closes #20194

Fix bug where replies to commit notes displayed in the MR discussion tab wouldn'…

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/20157

See merge request !5446

Add gitlab-workhorse version to admin dashboard

## What does this MR do?
Add gitlab-workhorse version to admin dashboard.

## What are the relevant issue numbers?
Closes #15418 

## Screenshot
![Zrzut_ekranu_2016-07-20_o_23.20.55](/uploads/ba6761e2145d903ac87bc7198bc8b182/Zrzut_ekranu_2016-07-20_o_23.20.55.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Add test - show Gitlab Workhorse version on Admin Dashboard
  - [x] All builds are passing
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)

cc @ubudzisz @yorickpeterse @grzesiek [@chastell](https://github.com/chastell) [@tomash](https://github.com/tomash)

See merge request !5321

Fix bug where replies to commit notes displayed in the MR discussion tab wouldn't show up on the commit page

Improve project rename log messages for better debugging

This should help diagnose issues such as #20178.

See merge request !5450

Add light border to rounded avatars

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/20128

To make it clear that avatar is cropped by border radius

cc @hazelyang 

See merge request !5429

Helping to diagnose #20178

Test for showing GitLab Workhorse version on Admin Dashboard

Refactoring