Protect OmniAuth request phase against CSRF.

Addresses #2268.

See merge request !1793

Use apt repositories to upgrade Docker images to the latest versions

Reduces the need to bump versions periodically.

See merge request !647

Reduces the need to bump versions periodically.

Use SIGKILL by default in Sidekiq::MemoryKiller

This makes the memory growth-triggered Sidekiq restarts more reliable by
reducing the chance that Sidekiq ends up in a state where it is not
accepting new jobs but also not shutting down: SIGKILL is more likely to
work than SIGTERM.

See merge request !1824

This makes the memory growth-triggered Sidekiq restarts more reliable by
reducing the chance that Sidekiq ends up in a state where it is not
accepting new jobs but also not shutting down: SIGKILL is more likely to
work than SIGTERM.

Batch 1 of text improvements

Batch 1 of changes from my effort at !635 to walk through every piece of text in GitLab and see if it can be improved.

This batch includes:

- Improve text on error pages.
- Improve Git access error messages.
- Improve description of branch protection levels.
- Improve OAuth signup error message.
- Improve OAuth application flash messages.

cc @rspeicher

See merge request !642

Version check

See merge request !1509

Extract handling of relative file links to its own HTML filter

Call merge request web hook for each commits

defreeze code

Fixes #2166.

See merge request !1820

Call merge request web hook every times a new commit hits the
source branch
Signed-off-by: Arthur Gautier <baloo@gandi.net>

Replace outdated gif in README with link to website

Fixes #2298

See merge request !1806

Fix bug where avatar filenames were not actually deleted from the database during removal

This would result in a 404 error in certain views.

The `save` call was being rolled back due to an error in the validation step.
Relax the validation step so that this works.

Closes #1570

See merge request !620

Don't accidentally unblock auto created users from Active Directory.

Fixes #1581.

See merge request !638

Update docs in line with mysql-postgresql-converter changes.

See merge request !640

Update migration style guide

See merge request !1823

Show user roles by comments.

I think it would be useful to show the user's role (Owner/Master/Developer/Reporter) by comments on GitLab.com (like GitHub does with Owner/Collaborator). That way people will know that when someone from the project's core team comments, they're not just some random user, but they're actually on the team. Currently they have the gather this from context.

![Screen_Shot_2015-05-12_at_12.15.45](https://gitlab.com/gitlab-org/gitlab-ce/uploads/0da0eea2087d6d3b14a2c0c594575c8a/Screen_Shot_2015-05-12_at_12.15.45.png)

On hover, the note actions replace the role:

![Screen_Shot_2015-05-12_at_12.17.32](https://gitlab.com/gitlab-org/gitlab-ce/uploads/54a83c2f5047ea3ce0387f6692b14fe5/Screen_Shot_2015-05-12_at_12.17.32.png)

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Addresses internal issue https://dev.gitlab.org/gitlab/gitlabhq/issues/2321.

cc @sytses

See merge request !639

Add SystemNoteService class

The Note model was basically two models crammed together - one handling user-created notes
(i.e., comments on things) and one handling system-created notes (i.e., references).
This splits out the system-specific stuff to a new SystemNoteService class.

See merge request !595