Changes calendar activities to use target reference

## What does this MR do?

Uses the targets reference in the calendar activities list. Previously it was using `#` which is wrong for merge requests.

## Screenshots (if relevant)

![Screen_Shot_2016-06-29_at_14.29.08](/uploads/4c52bbc7ca68d7b25e5bfb11ea55eef7/Screen_Shot_2016-06-29_at_14.29.08.png)

See merge request !4992

Removed fade when filtering results

## What does this MR do?

Removes the `opacity` change when filtering results seeing as we now do `Turbolinks.visit` it isn't required.

Best way to see issue - filter issues & then go back. Will still have opacity styling.

See merge request !4932

Bugzilla Integration

## What does this MR do?
Adds Bugzilla as a project service for external issue tracking

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

## Why was this MR needed?
Provides a notable Bugzilla option for use as an external issue tracker.  Existing Custom Issue tracker can be used to setup Bugzilla but this makes it clear that Bugzilla is an option.

## What are the relevant issue numbers?
Closes #14669

## 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)
- [ ] API support 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)


See merge request !4930

Add fog-rackspace microgem to support backups using rackspace provider

## What does this MR do?

Adds fog-rackspace gem to Gemfile.

## Why was this MR needed?

Because fog moved the rackspace provider to separate gem.

## What are the relevant issue numbers?

#19197

See merge request !4986

Use update_columns to by_pass all the dirty code on active_record

See merge request !4985

We think this is valid because we’re just storing new data that always will be valid

Reduce overhead and optimize ProjectTeam#max_member_access performance

See merge request !4973

The previous implementation would load the entire team member list and their
respective attributes. Now we only search for the user's specific
access level.

In gitlab-com/operations#42, this reduces the overall overhead of rendering
the issue from 28% to 20%.

First step of optimizing #19273

rebased with latest changes from master

Rebased to resolve merge conflicts

Requested in #14669

Added note to changelog

PipelinesFinder use git cached data

See merge request !4984

Fixes missing avatar on system notes

Closes #17295


![Screen_Shot_2016-06-27_at_12.50.50_PM](/uploads/b142226e608ccfe751a9b6059f57c9ec/Screen_Shot_2016-06-27_at_12.50.50_PM.jpg)

See merge request !4954

Markdown toolbar inserts code blocks

## What does this MR do?

Adds the ability to insert code blocks with the markdown toolbar buttons. This is done by selecting the block & then clicking the code button.

## What are the relevant issue numbers?

Closes #19173 


See merge request !4950

Fixed avatar alignment in new MR view

## What does this MR do?

Fixes the alignment of the avatar in new MR view.
Closes #19076 

## Screenshots (if relevant)

![Screen_Shot_2016-06-24_at_12.53.58](/uploads/fc94faf2e48f194852693b7ae79e8fa3/Screen_Shot_2016-06-24_at_12.53.58.png)

See merge request !4901

Workhorse to serve email diffs

See merge request !4590

Show basic system info on admin panel. Closes #18886

![Screen_Shot_2016-06-23_at_10.57.07_AM](/uploads/df33bc3dc36ceaf86f5e479ca15b83f3/Screen_Shot_2016-06-23_at_10.57.07_AM.png)

See merge request !4858

Fix group visibility form layout in application settings

## What does this MR do?

This fixes UI consistency related to setting group visibility levels in application settings. See screenshots.

## Screenshots (if relevant)

#### Before

![visiblity_consistency](/uploads/9cf9b517e25cd661ac61bdd7ca2d82f4/visiblity_consistency.png)

#### After

![group_visibility_after](/uploads/7b317684d047716f2aa5e60d19a4281b/group_visibility_after.png)

See merge request !4848

Closes #18949

Fixed dropdown not filtering queries entered before data is loaded

## What does this MR do?

Triggers a 'keyup' event on a filters input to force it to process any text that was added before the data was retrieved and rendered.

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

😕 

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #18942.

## 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
- [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 !4846

[ci skip]

Fix CHANGELOG

Fixes double header for 8.9.3 entries

See merge request !4971