Remember user's inline/tabular diff view preference in a cookie

_Originally opened at !1677 by @kkm._

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As per #3071, some users (we have a local EE installation) prefer 2-column view in diff. In this MR I add an implementation for this feature, using a cookie.

Fixes #3071.

See merge request !2723

Rearrange some sections in CONTRIBUTING.md

- Move 'Merge request description format' and
  'Contribution acceptance criteria' under 'Merge requests'
- Link to doc_styleguide where appropriate
- Provide markdown template for merge requests

See merge request !2748

[ci skip]

Add table of contents in CONTRIBUTING.md



See merge request !2745

Clarify when JIRA service was backported to CE



See merge request !2744

[ci skip]

[ci skip]

Change logo image name in markdown documentation

Closes #13233

See merge request !2743

[ci skip]

fixed Windows commands in SSH Help.

The current commands shown don't work in Command Line, or PowerShell. Command Line doesn't recognize the `~` character as the home directory, the `<` character is reserved in PowerShell, and `cat` doesn't work in Command Line. This commit provides commands that will work for both the Command Line, and PowerShell.

See merge request !2694

Changed the project switcher dropdown toggle

Moved the positioning of the dropdown to be more aligned with the title

Closes #13219 and #13214 

cc. @jschatz1 @dzaporozhets 

See merge request !2733

Dedicated method for counting commits between refs

Corresponding gitlab_git merge request: https://gitlab.com/gitlab-org/gitlab_git/merge_requests/66
Issue that lead to these changes: https://gitlab.com/gitlab-org/gitlab-ce/issues/12619

See merge request !2707

[ci skip]

Feature/jschatz1/sidebar features

* Changes sidebar width (290px).
* Makes shortcuts for <kbd>j</kbd> and <kbd>k</kbd> keys for next and previous issues.

![Screen_Shot_2016-02-05_at_3.06.22_PM](/uploads/8590be43dc1b9feffd4f32b4e8cb7790/Screen_Shot_2016-02-05_at_3.06.22_PM.png)

cc/ @dzaporozhets 

See merge request !2734

Fix diff and commit view on merge requests

with new sidebar
Fixes #3981

See merge request !2718

Fixes for issue with poor logo transition animation on Safari

See merge request !2690

updates after code review: moved coffee code to appropriate file, updated css to not use js-prefixed selectors

Updated comments and Changelog

Removed duplicate line in changelog

Improve placeholder: search -> Search
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !2732

Moved the positioning of the dropdown to be more aligned with the title

Closes #13219 and #13214

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

Thanks @rspeicher

Change edited icon to word.
Change edited text color to gray
cc/ @creamzy

Make sure the public/uploads/ directory is created



See merge request !2730

Fix double paging

![Screen_Shot_2016-02-05_at_10.27.34_AM](/uploads/a21ad6c47ddecad29d377497ee2a167d/Screen_Shot_2016-02-05_at_10.27.34_AM.png)

![Screen_Shot_2016-02-05_at_10.27.44_AM](/uploads/3badb423df25f009886138c65cfe8347/Screen_Shot_2016-02-05_at_10.27.44_AM.png)


See merge request !2727

[ci skip]

Improve admin broadcast messages page

* Show latest broadcast messages first on admin page
* Use nice looking pagination
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixes #13211 

cc @rspeicher @DouweM 

See merge request !2725

Fix Ruby SHA in installation guide

The Ruby SHA that we were checking against in the
installation guide was wrong. I replaced it with
sha256sum which is also present in the Ruby downloads
page. Also added it as a note in the doc styleguide. 

See merge request !2726

[ci skip]

Page project list on dashboard



See merge request !2689

* Show latest broadcast messages first on admin page
* Use nice looking pagination
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>