Experimental support for gitlab-git-http-server

https://gitlab.com/gitlab-org/gitlab-git-http-server

This change introduces the GITLAB_GRACK_AUTH_ONLY environment
variable. When set, Grack requests to GitLab will only respond with
the user's GL_ID (if the request is OK) or an error. This allows
gitlab-git-http-server to use the main GitLab application as an
authentication and authorization backend.

If we like how this works we should drop the GITLAB_GRACK_AUTH_ONLY
variable at some point in the future.

See merge request !1915

To make Rubocop and Douwe happy

New document in GitLab Basics about adding new files



See merge request !1913

Added info about repo size

Because of tweet https://twitter.com/s_hulard/status/624160758335672320

See merge request !1912

https://gitlab.com/gitlab-org/gitlab-git-http-server

This change introduces the GITLAB_GRACK_AUTH_ONLY environment
variable. When set, Grack requests to GitLab will only respond with
the user's GL_ID (if the request is OK) or an error. This allows
gitlab-git-http-server to use the main GitLab application as an
authentication and authorization backend.

If we like how this works we should drop the GITLAB_GRACK_AUTH_ONLY
variable at some point in the future.

Added note about SSH keys being unique

Because of issue https://gitlab.com/gitlab-com/support-forum/issues/143

See merge request !1914

Added note about labels in MR

because of tweet https://twitter.com/apoirier1/status/624197308759035905

See merge request !1911

Added Fork Project document to GitLab Basics



See merge request !1909

Use project repository expire_cache to clear cache in test

Clearing the entire Redis cache in 643557da for the `branches_spec.rb` may be causing issues. Just clear what we need.

See merge request !1022

the repository expire_cache method

Remove 7.14 entry that was pushed to 7.13

See merge request !1020

Fix 404 error in files view after deleting the last file in a repository

Here's the logic:

1. In `TreeController`, `require_non_empty_project` will prevent `show` from being called if the project is  empty. That means all calls to `show` will be guaranteed to have at least 1 commit.
2. If the ref name is not valid, then return a 404. This ensures that at least the controller is looking at a valid branch/tag/SHA ID.
3. This leaves a number of cases:

```
3a. Valid ref, valid directory
3b. Valid ref, valid filename
3c. Valid ref, invalid path
3d. Valid ref, no files
```

Case 3a: The tree will not be `empty?` and will pass through the whole function.

Case 3b: The tree will be `empty?` but the `blob_at` will resolve properly and trigger a redirect to the file.

Case 3c: In this case, a path is given. Return 404 if it cannot be resolved neither as a tree nor a blob.

Case 3d: In this case, no path is given. If the tree is empty, this means it's an empty branch and just fall through.

Example broken branch: https://gitlab.com/gitlab-org/gitlab-test/tree/empty-branch

Closes #1362

See merge request !1010

Fix full screen mode for snippet comments

ZenMode is now initialized for snippet pages.

Fixes #2036.

See merge request !1016

Closes #1362

ZenMode is now initialized for snippet pages.

Fixes #2036.

You need to store your DB encryption key

You can break two-factor authentication for existing users when
restoring a backup if you lost your DB encryption key.

See merge request !1015

Update changelog



See merge request !1013

Don't stop if database.sql.gz already exists

The existing behavior of the backups is to overwrite whatever data
was still there in the scratch directories. This broke when we added
a 'gzip' step because 'gzip database.sql' will fail if 'database.sql.gz'
already exists. Doing 'rm -f database.sql.gz' before the 'gzip'
avoids this failure.

See merge request !1011

The existing behavior of the backups is to overwrite whatever data
was still there in the scratch directories. This broke when we added
a 'gzip' step because 'gzip database.sql' will fail if 'database.sql.gz'
already exists. Doing 'rm -f database.sql.gz' before the 'gzip'
avoids this failure.

Fix change log for 7.11 and move entry to 7.12

The change log for 7.11 was accidentally split in
3865a1d9. Additionally, the change added
with this commit did not make it into 7.11 according to
`git branch --contains` and it has not been cherry picked to 7-11-stable
so the entry is moved to 7.12.

Refs GH-5625, GH-9318.

See merge request !1009

The change log for 7.11 was accidentally split in
3865a1d9. Additionally, the change added
with this commit did not make it into 7.11 according to
`git branch --contains` and it has not been cherry picked to 7-11-stable
so the entry is moved to 7.12.

Refs GH-5625, GH-9318.

[ci skip]

GoogleCode importer: Do not care about casing of image file extensions

When a GoogleCode repository contains an attached image with an UPPERCASE file extension, it's not inlined.

/CC @DouweM

See merge request !1003

Fix (i.e. prevent) access to disabled features for unauthenticated users

Unauthenticated users had access to disabled features of public
projects. The code has been slightly refactored so that feature checks
are done in a separate method and can also be applied for public access.

See merge request !1006

merge_requests: add fetch command to the MR page

In our instance, users asked for an easy way to get the contents of the MR into their local clone. This adds a command line which can be used to fetch the contents of the MR.

Screenshot:

![fetch-command](https://gitlab.com/gitlab-org/gitlab-ce/uploads/d83acfbdb69f023d13b45dff5d583ac1/fetch-command.png)

See merge request !678

Remove repository graph log to fix slow cache updates after push event

Recalculating `graph_log` took minutes on a large repository since each
of the 6000 commits would need to calculate the diff. Since graph_log
does not appear to be used, remove it from the list of things to update.
For the Linux kernel repository, this reduced the `ProjectCacheWorker` time
from 8+ minutes to 16 seconds.

Closes #2016

See merge request !1005