Parallel diff refactor

Refactor side-by-side diff to remove code duplication.

Base the side-by-side diff on inline diff code.

In first iteration:

1. commenting on the side-by-side diff is not possible
1. no expanding of the surrounding code

See merge request !1066

Added search wiki feature

Wrap arguments for `[ -z` in double quotes

See merge request !1071

Add ci to blacklist

See merge request !1075

Close button after added comment

Fixes #1549

See merge request !1070

API: Project create docs miss path argument

Fixes #1551

See merge request !1074

Refactor diffs

This refactoring done on top of Marin improvements to side-by-side diff.
Main target of this refactoring is to reduce mess and increase test coverage.

1. Use objects:
  * Gitlab::Diff::Line for line change in diff
  * Gitlab::Diff::File for file changes (diff + blob info)
2. Avoid `yield` magic
3. Move logic from views/helper to models/libs
4. Move diff views under separate dir `app/views/projects/diffs`

See merge request !1072

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

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

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

Adding in snippet search functionality

Fix images on github

Fixes https://dev.gitlab.org/gitlab/organization/issues/55

/cc @job @dzaporozhets

See merge request !1073

Conflicts:
	CHANGELOG

add missing config files to check during release process

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

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

Change keyboard shortcut for activity to project

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

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

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

Omniauth doc

Fixes #1481

See merge request !1069

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

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

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

update ssl_ciphers

Update markdown reference to external issues

change bash to sh in web, background_jobs scripts