Unused gon variable with very bad performance

## What does this MR do?

Remove an unused variable with a lot of performance penalty. It was opening a transaction just to return a constant string.

## Does this MR meet the acceptance criteria?

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

See merge request !4969

In any case if just want the value which is always ‘gitlab’

require 'benchmark/ips'

Project.first # To load database things
GitlabIssueTrackerService.first # To load database things

Benchmark.ips do |x|
  x.config(:time => 5, :warmup => 2)

  x.report("current") do
    Project.new.default_issue_tracker.to_param
  end

  x.report("") do
    'gitlab'
  end

  x.compare!
end

Calculating -------------------------------------
             current     4.000  i/100ms
                        30.938k i/100ms
-------------------------------------------------
             current     47.298  (±10.6%) i/s -    232.000 
                          4.366M (±20.9%) i/s -     17.202M

Comparison:
                    :  4366456.0 i/s
             current:       47.3 i/s - 92318.26x slower

docs: fix default_branch_protection default



See merge request !4479

Switched mobile button icons to ellipsis and angle

## What does this MR do?
Switches the mobile button icons

## What are the relevant issue numbers?
Closes #19170   
Part of #19200 

## Screenshots (if relevant)
![Screen_Shot_2016-06-27_at_9.08.28_AM](/uploads/7784489402e342e671d02b24d2ea0d64/Screen_Shot_2016-06-27_at_9.08.28_AM.png)


See merge request !4944

Resolve "Pin should show up at 1280px min"

## What does this MR do?
Decreased window min width for pinned sidebar

## What are the relevant issue numbers?
Closes  #19171    
Part of #19200 

## Screenshots (if relevant)
![Screen_Shot_2016-06-27_at_9.36.13_AM](/uploads/d0a87bca5af1bee808c5b1046c0ecf72/Screen_Shot_2016-06-27_at_9.36.13_AM.png)

See merge request !4947

Use GIT_DEPTH for builds

## What does this MR do?
Enables experimental feature to use shallow cloning. 

## Why was this MR needed?
To speed up the builds and reduce the pressure on NFS servers. This should save us between 30s to 1m of the time of each build.

## More information
 `GIT_DEPTH`: https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/merge_requests/188

## Problems
- Too small value for `GIT_DEPTH` can make it impossible to retry old changes.
You will see `unresolved reference` in build log.
We should then reconsider changing `GIT_DEPTH` to higher value
- Mechanism that rely on `git describe` may not work correctly when `GIT_DEPTH` is set. This will happen, because only part of the git history is present on the build machine

## Requirements
GitLab Runner 1.3.0. Currently all our internal runners use beta release or 1.3.0 with support for `GIT_DEPTH`.

@pcarranza Please decide when to merge that. We should start monitoring to see an impact on our NFS servers.

cc @jacobvosmaer-gitlab @pcarranza 


See merge request !4730

Add SMTP upgrade information

8.8 to 8.9 requires an update to the SMTP settings for source installs.

See merge request !4966

Closes #19252

[ci skip]

Refactor GitLab architecture document

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/14236

See merge request !3694

Display last commit of deleted branch in push events

## What does this MR do?

Display the last commit of a deleted branch in the push events of a project.

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

Is the change in `app/models/event.rb` the correct way to display a two-line event for deleted branches?

## Why was this MR needed?

It is easier to restore an accidentally deleted branch if the commit hash is displayed in the push events.

## What are the relevant issue numbers?

Fixes #18659

## Screenshots

### Before garbage collection

![before-gc](/uploads/5674cd53e1564d48b7f2f8406ea0fbed/before-gc.png)

### After garbage collection

![after-gc](/uploads/80950c1932feeb3b69d0fc11b8f7acf4/after-gc.png)

See merge request !4699

Fix encrypted data backwards compatibility after upgrading attr_encrypted gem

Adds missing attribute to attr_encrypted so it is fully backwards-compatible. Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19073

See merge request !4963

Add custom highlighting via .gitattributes

## What does this MR do?
Allows user control of language selection via a `gitlab-language` entry in `.gitattributes`

## Are there points in the code the reviewer needs to double check?
(paired with @stanhu)

## Why was this MR needed?
Guessing languages by filename is fraught and often wrong. In one project, `foo.pl` may be perl, and in another it may be prolog. Users might have a Thingfile that needs ruby highlighting, or depend on things that can't work in general, like `*.C` (capitalized) mapping to C++ instead of C.

This allows the user to override language choice so they never have to look at a mis-highlighted file.

## What are the relevant issue numbers?
https://github.com/jneen/rouge/issues/494
https://gitlab.com/gitlab-org/gitlab-ce/issues/13818 (*.tpl can't in general map to Smarty)
https://gitlab.com/gitlab-org/gitlab-ce/issues/13615 (in cases we don't have a language and mis-identify it, users could map to 'text' to turn off highlighting)

## Screenshots (if relevant)

## 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 (N/A)
- [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 !4606

This reverts commit b435d7405364d28ec364072f4437512da2876762.

paired with @stanhu

Rename Licenses API to License Templates API

## What does this MR do?

Earlier I renamed this in EE, thinking license templates was an EE-only feature. This backports that change to CE. Thanks to @vsizov for pointing out this error.

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/400 for the EE merge request. 

See merge request !4957

Check for conflict with wiki projects when creating a new project.

## What does this MR do?
Check for conflict with wiki projects when creating a new project
## Are there points in the code the reviewer needs to double check?
No
## Why was this MR needed?
To avoid exposing the information from the wiki repository of other project
## What are the relevant issue numbers?
#18398 
## Screenshots (if relevant)
![Screen_Shot_2016-06-24_at_6.03.49_PM](/uploads/7bf55e5159bf0c2b653b8f4f941f72fc/Screen_Shot_2016-06-24_at_6.03.49_PM.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
- [ ] 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 !4918

Fix visibility of snippets when searching

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/18997

See merge request !1972

Fix an information disclosure when requesting access to a group containing private projects

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19102.

The commit speaks for itself:

    Fix an information disclosure when requesting access to a group containing private projects
    
    The issue was with the `User#groups` and `User#projects` associations
    which goes through the `User#group_members` and `User#project_members`.
    
    Initially I chose to use a secure approach by storing the requester's
    user ID in `Member#created_by_id` instead of `Member#user_id` because I
    was aware that there was a security risk since I didn't know the
    codebase well enough.
    
    Then during the review, we decided to change that and directly store the
    requester's user ID into `Member#user_id` (for the sake of simplifying
    the code I believe), meaning that every `group_members` / `project_members`
    association would include the requesters by default...
    
    My bad for not checking that all the `group_members` / `project_members`
    associations and the ones that go through them (e.g. `Group#users` and
    `Project#users`) were made safe with the `where(requested_at: nil)` /
    `where(members: { requested_at: nil })` scopes.
    
    Now they are all secure.

See merge request !1973