GitHub importer use default project visibility for non-private projects

## What does this MR do?

GitHub importer use the `Default Project Visibility` setting for all non-private projects.

## Why was this MR needed?

This allow users to import projects when `Public` visibility is restricted.

## What are the relevant issue numbers?

Fixes #21437

See merge request !6023

Refactor ability.rb into Policies

## What does this MR do?
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

Add a BroadcastMessage API

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/21628

See merge request !6112

Fix bug where pagination is still displayed despite all todos marked as done

## What does this MR do?
Changes the todo `mark all as done` button callback to remove pagination and add user friendly text `"You're all done!"` so that it is consistent with what the page should look like after refreshing

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

## Why was this MR needed?
Resolve existing UI inconsistency

## Screenshots (if relevant)
Before:
![8xDRiXB1TL](/uploads/479edbdedf8d468b4c5e502f36a0c19f/8xDRiXB1TL.gif)

After:
![q4XDxhujPX](/uploads/3566eb538e6ad5a2d32b78351b9bc47d/q4XDxhujPX.gif)

## 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
  - [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 #21048

See merge request !6113

Check for existance of elements under test in application_spec.js

## What does this MR do?

Checks that the elements under test in `application_spec.js` actually exist.

## Why was this MR needed?

```
$ echo 'just garbage' > spec/javascripts/fixtures/application.html.haml 
$ bundle exec teaspoon spec/javascripts/application_spec.js 
2 examples, 0 failures
```

See merge request !6051

Fixed escaping issue with labels filter

## What does this MR do?

Encodes label names to stop any JS errors.

## What are the relevant issue numbers?

Closes #15552

See merge request !6123

Remove redundant js-timeago-pending from user activity log

## What does this MR do?
Enables the `skip_js` feature of `time_ago_with_tooltip()` since the frontend was already re-initializing `timeago` on all the elements after it received the data from the backend.

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

## Why was this MR needed?

*  Reduces bandwidth usage (Reduced by ~3.1kb)
*  Removes redundant code
*  Happy DOM 🎈 

## What are the relevant issue numbers?
Closes #21063 

## Screenshots (if relevant)
Before (DOM):
![Screen_Shot_2016-08-18_at_11.14.18_AM](/uploads/8be02cff27e452670988db8ff54bd57c/Screen_Shot_2016-08-18_at_11.14.18_AM.png)

After (DOM):
![Screen_Shot_2016-08-18_at_11.26.51_AM](/uploads/a0c5cbcd4c7b8e524a848b50dbd88c55/Screen_Shot_2016-08-18_at_11.26.51_AM.png)

Before (Bandwidth):
![Screen_Shot_2016-08-18_at_11.28.24_AM](/uploads/c37de0b398d7c66770f1def1777ca11a/Screen_Shot_2016-08-18_at_11.28.24_AM.png)

After (Bandwidth):
![Screen_Shot_2016-08-18_at_11.29.49_AM](/uploads/dc21719b965df1e73c868470447a1b20/Screen_Shot_2016-08-18_at_11.29.49_AM.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 !5871

Filters tags by name

Closes #21673 

See merge request !6121

Fix sorting issues by "last updated" after import from GitHub

## What does this MR do?

Don't touch Issue/Merge Request when importing GitHub comments as it will trigger an update on `updated_at` field. It also use `updated_at` as the last updated date doesn't matter the Issue/Pull Request state.

## Why was this MR needed?

After import from GitHub, sorting issues by "last updated" doesn't work as expected.

## What are the relevant issue numbers?

Fixes #21567

See merge request !6110

Fix toggler_behavior.js to toggle ajax loaded contents like `diffs` page.

## What does this MR do?

Fix toggle in diffs

## What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/21676, https://gitlab.com/gitlab-org/gitlab-ce/issues/21686.

See merge request !6119

Fixed invisible scroll controlls on build page on iPhone

## What does this MR do?
Fixes invisible scroll controls on build page on iPhone

## Are there points in the code the reviewer needs to double check?
No.

## Why was this MR needed?
Because it's not correct behavior.

## Screenshots (if relevant)

| Before | After |
| -------- | -------- |
| ![IMG_0424](/uploads/19a6b498ad8be265e52619b9e7b71975/IMG_0424.PNG)   | ![IMG_0425](/uploads/3f7a7e00475a2e4c78e77e3bc76ac9f3/IMG_0425.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
- [ ] 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)

## What are the relevant issue numbers?
Not found

See merge request !6125

Fix Sentry not reporting right program for Sidekiq workers

Moves program tag into the global configuration since this doesn't change and since Sidekiq workers get a unique context for each event.

Closes #21410

See merge request !6004

Fix wording in PROCESS.md

Simple grammar fix (those issue -> those issues)

See merge request !6131

Fix repo title alignment

## What does this MR do?
Adds an extra pixel margin to the hamburger button so that it matches the baseline of the repo title

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

## Why was this MR needed?
Resolve UI Inconsistency

## What are the relevant issue numbers?
Closes #21408 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-25_at_8.44.11_PM](/uploads/e18241f3f025c501427f28d9040ca898/Screen_Shot_2016-08-25_at_8.44.11_PM.png)

After:
![Screen_Shot_2016-08-25_at_8.43.45_PM](/uploads/03eca5df535af12eff7b79109a6b6f23/Screen_Shot_2016-08-25_at_8.43.45_PM.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 !6046

Block concurrent pipeline processings

## What does this MR do?

It's possible that two builds that succeed at the same will try to
concurrently process pipeline. This can lead to scenario when it will
fail to trigger next stages.

This MR makes sure that process of updating is blocking.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/21263

See merge request !6090

API: Expose issue confidentiality flag.

## What does this MR do?

This MR adds support for confidential issues the the API. The property as exposed and users can create or update confidential issues.

## What are the relevant issue numbers?

Closes #17199 

See merge request !5384

The ID of a project can be also a string

## What does this MR do?

Add the integer type for the project's ID in the API docs.

## What are the relevant issue numbers?

Missed a few spots in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6102

See merge request !6133

[ci skip]

Minor code refactor for inlining functions in logo JS.

See merge request !6097

Create bitmaps during 'git gc'

## What does this MR do?

Add instructions to enable creation of Git packfile bitmaps.

## Why was this MR needed?

Because we still are not using Git packfile bitmaps in GitLab

[ci skip]

See merge request !6104

Don't expose a user's private token in the `/api/v3/user` API

## Why was this MR needed?

A user's private token is being leaked in the `/api/v3/user` API.

## What are the relevant issue numbers?

- Closes #20911

## Does this MR meet the acceptance criteria?

- [ ]  #20911 !6047 Application-Specific Tokens Are Insecure
    - [x]  Implementation
    - [x]  Test
    - [x]  CHANGELOG
    - [x]  Make sure build is green
    - [x]  Assign to endboss
    - [ ]  Wait for merge


See merge request !6047

Allow setting branch refs for MR

@dbalexandre can you take a look please?

See merge request !6025

Added performance guidelines for new MRs

## What does this MR do?

This MR adds a set of guides that should be followed by merge request authors.

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

Spelling, grammar, etc

## Why was this MR needed?

There is no set of guidelines one should follow when submitting merge requests. This leads to developers at times disregarding performance. This in turn results in performance specialists having to clean up the mess, or production engineers being woken up in the middle of the night because the database is on fire.

## 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)
- 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)

cc @DouweM @rspeicher @pcarranza @dzaporozhets 

See merge request !5905

Remove redundant pipeline tooltips from short labels

## What does this MR do?
Removes the tooltips from labels that have less than 12 characters, so that the tooltips only show when the pipeline labels are truncated

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

## Why was this MR needed?
Removes unnecessary tooltips for non-truncated pipeline labels

## Screenshots (if relevant)
Before:
![NjBCzZ63NK](/uploads/2c5627f3000ceeeb134452a6619734f2/NjBCzZ63NK.gif)

After:
![EHsGdjGi3F](/uploads/ffdc6f9c8e807ca4eaf576ee6a660798/EHsGdjGi3F.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)

## What are the relevant issue numbers?
#21542

See merge request !6058