Resolve Merge conflicts in editor

## What does this MR do?

This is the second iteration of https://gitlab.com/gitlab-org/gitlab-ce/issues/20344 which now allows to resolve conflicts manually providing an editor to the user.

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

- Previous implementation has been refactored almost from the ground up.
- Also some components like `parallel-conflict-lines` has been optimized to work well with PhantomJS.
- The app and files required files are loaded only when needed. `merge_conflicts_bundle.js` is only loaded in `/<group>/<project>/merge_requests/<Id>/conflicts` only

## Why was this MR needed?

Some MRs were unable to be solved interactively in the UI, with this MR we let the user to manually fix complex merge request conflicts.

## Screenshots (if relevant)

<img src="/uploads/33a016f025bd590b1fc6eeee1ee11626/Screen_Shot_2016-09-19_at_1.39.39_PM.png" width="800">

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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)

## What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/20344, https://gitlab.com/gitlab-org/gitlab-ce/issues/3567.

See merge request !6374

Fixes endpoint to username validator

Fixes failing specs on master. Introduced here https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6328

See merge request !6951

Apply better hierarchy to markdown headers and issue/mr titles

## What does this MR do?
Applies better hierarchy to markdown headers and issue/mr titles

## Why was this MR needed?
Titles of issues/mr's were smaller than h1, leading to strange hierarchy when reading descriptions

## Screenshots (if relevant)

### Before:
![Screen_Shot_2016-10-14_at_1.31.37_PM](/uploads/79b6b16b8ed1b3b49578161eea1f0e42/Screen_Shot_2016-10-14_at_1.31.37_PM.png)

### After:
![Screen_Shot_2016-10-14_at_1.31.26_PM](/uploads/f710b63c112e342c5429810984079da6/Screen_Shot_2016-10-14_at_1.31.26_PM.png)

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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 it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #21395

See merge request !6904

Fix toggling of expand/hide pipeline graph button

## What does this MR do?

Corrects the toggling behaviour given that the pipeline graph now starts in a different state.

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

## Why was this MR needed?

Expand/hide toggling UI is buggyyy

## Screenshots (if relevant)

![2016-10-14_18.15.41](/uploads/7cdeef02c0b8aa4266f2878866e4b633/2016-10-14_18.15.41.gif)

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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 it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #23358

See merge request !6898

Rename users routing from /u/:username to /users/:username for
consistency with other routes

Renames /u/:username to /users/:username

To follow consistency with other routes (like groups) and
UsersController name.
Now when you can use `/:username` for accessing user page there is no
need in shortcut like `/u/`

See merge request !6851

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixed find file keyboard navigation

## What does this MR do?

The code to view a file on find file page was removed, this adds that back in & adds some tests.

## What are the relevant issue numbers?

Closes #23423

See merge request !6944

Resolve "No space between buttons on Files page"

## What does this MR do?

Adds a `.download-button` class to the project download button and added `10px` of margin to this button within the `.tree-controls`.

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

## Why was this MR needed?

Whitespace is gr8!

## Screenshots (if relevant)

![Screen_Shot_2016-10-16_at_14.05.09](/uploads/2da692bd55e06c730d048ccf9173bd2c/Screen_Shot_2016-10-16_at_14.05.09.png)

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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 it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #23380

See merge request !6921

Enable activerecord_sane_schema_dumper for test

## What does this MR do?
Enable `activerecord_sane_schema_dumper` for test allowing to use `test` database for consistent schema generation.

See merge request !6931

Closes #23423

Updated logo from @luke

Closes #23274

See merge request !6942

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix broken specs on MySQL

## What does this MR do?
Fixes broken master after https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6896

See merge request !6935

Fix Test Env (proper error handling when gitlab-shell is not clonned)

## What does this MR do?

If we were not able to clone gitlab-shell we have to stop all test suite, for now we run it regardless we cloned it or not.

## Why was this MR needed?

To not confuse developers when build is red, to get fasts feedback, to save resources and time.

See merge request !6933

Fix Safari displaying NaN for selected due date

## What does this MR do?

1. Stops using `Date.parse` to parse selected due dates. 
2. Refactors DueDateSelectors to be more maintainable and readable

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

**To review the actual fix, look here:** https://gitlab.com/gitlab-org/gitlab-ce/commit/4ad43ac3a12902d7ea01dc09f8a361b01c21a0ee. It would be difficult to pick out from the overall diff. 

## Why was this MR needed?

In Safari, the due date selector was displaying 'NaN' when a date is selected, which was being returned by `Date.parse`. Because `Date.parse` is implemented differently across browsers it's generally recommended to favor implicit Date parsing with the `Date` constructor. For more background on this, [see MDN on Date.parse](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Date/parse).

Also, the code for DueDateSelector was pretty messy, and its logic was very tightly coupled, so I refactored it. None of the basic logic changed, I just broke it up into smaller pieces and made it more OO. 

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/22984

See merge request !6797

Fix randomly crashing spinach test for merge request

For https://gitlab.com/gitlab-org/gitlab-ce/issues/23378

See merge request !6932

Fix atom feed spinach failure

## What does this MR do?

Replaces all carriage returns in the expected commit description.

Is a partial fix to...

> spinach 5 10 https://gitlab.com/gitlab-org/gitlab-ce/builds/5132637 - partial fix in !6910

As you can see, the other half of the fix to this build is in !6910.

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

## Why was this MR needed?

Failed spinach tests

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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 it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

See merge request !6922

Add Pipeline metrics worker

## What does this MR do?
Creating a new Merge Request metrics is time consuming, because we need to access repository.

This makes this operation asynchronous, thus non-blocking for updating pipeline.

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

## Why was this MR needed?

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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 it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

See merge request !6896