Add rspec feature tests for the diff notes feature.

## What are the relevant issue numbers?

Closes #19957.

See merge request !5417

This fixes a long running tests due to changed Sidekiq state

## What does this MR do?
Fixes a ordering of tests problem, where GroupsController tests change global state and this affects IrkerService

cc @connorshea 

See merge request !5819

Allow to sort by project size on admin projects page

Fixes #20317

See merge request !5797

Add test coverage badge

## What does this MR do?

This MR adds a test coverage badge.

Test coverage badge will be a SVG image you can embed in README.md or on your website that will be created dynamically by GitLab, to show information about how much of the code is being covered by tests. In addition to coverage-regexp feature we currently have, this feature will make it possible to use the coverage data obtained from the build log. We will support both - pipeline coverage, or test coverage for particular job in the pipeline. 

![coverage_badges](/uploads/dfa307339eb58c8138e551b42c0d8756/coverage_badges.png)

![coverage_badge](/uploads/30406e4bdcf979b2900ffe8996728c97/coverage_badge.png)

## What are the relevant issue numbers?

Closes #3714

## 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 !5708

Fix pipeline and build seeds in development environment

## What does this MR do?

When we depend on state machine events in seeds, it is likely that we will break fixtures from time to time because when transition rules change, using events most likely invalidates some objects in seeds

## Why was this MR needed?

Pipeline and build seeds were broken in development environment.

## What are the relevant issue numbers?

Closes #20933

See merge request !5810

When we depend on state machine events in seeds, it is likely that we
will break fixtures from time to time because when transition rules
change, using events most likely invalidates some objects in seeds.

Add method missing from EE

## Why was this MR needed?

`ProjectWiki#repository_exists?` is present in EE but not on CE, and there's no particular reason why it shouldn't

See merge request !5802

Show deployment status on a MR view

## What are the relevant issue numbers?

Resolves #19571, one in the list of #19992

## Screenshots (if relevant)

external_url = nil
![Screen_Shot_2016-08-02_at_13.57.03](/uploads/20ea1587eea556c7a1acd0ff726a5bfb/Screen_Shot_2016-08-02_at_13.57.03.png)

external_url != nil
![Screen_Shot_2016-08-02_at_13.59.59](/uploads/0094b9ddece3f4bf76c83988840c096d/Screen_Shot_2016-08-02_at_13.59.59.png)

Note, the timings are weird between merging and deploying, that is because I did it in the wrong order.

## 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

See merge request !5622

Limit the size of SVGs when viewing them as blobs

## What does this MR do?

This MR prevents rendering of SVG blobs larger than 2 MB.

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

I couldn't figure out how to properly test the view for this as this requires a large SVG (inflating the repository size) _or_ stubbing, the latter doesn't really seem possible using Spinach and all the stuff potentially involved.

## Why was this MR needed?

When rendering large SVG blobs (e.g. 20 MB files) a request may time out and consume a lot of memory.

## What are the relevant issue numbers?

#1435

## Screenshots (if relevant)

![svg_notice](/uploads/c8de32522eda95a41a24555c3f85bfc1/svg_notice.jpg)

## 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~~
- Tests
  - [x] 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)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

cc @jschatz1 @annabeldunstone (there are some UI changes, see the above screenshot).

See merge request !5794

Use new PhantomJS version

## What does this MR do?
Makes CI builds to use PhantomJS 2.1.1.

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

## Why was this MR needed?

## What are the relevant issue numbers?

## 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
- [ ] 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)

See merge request !5740

Try to get back todo's cache or at least avoid hitting the database

See merge request !5789

Speed up todos queries by limiting the projects set we join with

See merge request !5791

This ensures that SVGs greater than 2 megabytes are not scrubbed and
rendered. This in turn prevents requests from timing out due to
reading/scrubbing large SVGs potentially taking a lot of time (and
memory). The use of 2 megabytes is completely arbitrary.

Fixes gitlab-org/gitlab-ce#1435

Follow-up 1003454c

Follow-up on 1003454c

Closes #20828