Increased zindex of layout nav

This fixes issues where group inputs would be above the dropdown in the nav

![Screen_Shot_2016-05-17_at_10.14.18](/uploads/08e4a43922051c28377ae6f34725ccc6/Screen_Shot_2016-05-17_at_10.14.18.png)

Closes #17524

See merge request !4176

Enable RSpec/NotToNot cop and auto-correct offenses

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/17761

See merge request !4267

Fixed issue with button color when no CI enabled

## What does this MR do?

Fixes an issue with the color of the merge button when no CI is setup.

## What are the relevant issue numbers?

Closes #17844

## Screenshots

![Screen_Shot_2016-05-25_at_09.58.44](/uploads/87aac74c5e2f8bfd2831e99c5915856d/Screen_Shot_2016-05-25_at_09.58.44.png)

See merge request !4287

Signed-off-by: Alfredo Sumaran <alfredo@gitlab.com>

Fix concurrent request when updating build log in browser

If you have a slow internet connection the trace will not be updated correctly. We need to check if our request is the latest one.

Fixes: https://gitlab.com/gitlab-org/gitlab-ce/issues/17535

See merge request !4183

Closes #17844

Fix backups if registry is disabled

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17749

See merge request !4263

Changed the Slack build message to use the singular duration if necessary

## What does this MR do?

Previously, the Slack build notification would say "second(s)" even when the duration was only 1 second. This MR fixes that. This is my first time writing Ruby code and my first MR on Gitlab, so feedback is very much appreciated!

See merge request !4253

This fixes issues where group inputs would be above the dropdown in the nav

Closes #17524

Update health_check.md - Fix spelling of admin/health_check path.  [ci skip]

## What does this MR do?
Fix the spelling of admin/heath_check to admin/health_check in health_check documentation

## Are there points in the code the reviewer needs to double check?
No

## Why was this MR needed?
Fix a spelling error that may mislead a user on the proper URL/Path to check the GitLab health.

## What are the relevant issue numbers?

## Screenshots (if relevant)

See merge request !4282

Updated snippets UI

![Screen_Shot_2016-05-18_at_14.11.54](/uploads/2544351e50f19a36c4ba9a7a92d5544b/Screen_Shot_2016-05-18_at_14.11.54.png)

Closes #14328

See merge request !4194

Project settings UI update

![Screen_Shot_2016-05-16_at_16.42.55](/uploads/2e308cbf26a002fc411c3e84b663a5d1/Screen_Shot_2016-05-16_at_16.42.55.png)![Screen_Shot_2016-05-16_at_16.43.01](/uploads/8d983c43307c65852efe002f6e9482d9/Screen_Shot_2016-05-16_at_16.43.01.png)![Screen_Shot_2016-05-16_at_16.43.16](/uploads/6124e0600cc0e5b309a60b065409d537/Screen_Shot_2016-05-16_at_16.43.16.png)![Screen_Shot_2016-05-16_at_16.43.13](/uploads/177976c2c08034e096e7ebdcad1f369f/Screen_Shot_2016-05-16_at_16.43.13.png)

See merge request !4162

Clicking changes tab scrolls the window to show the content

When you click on the changes tab in a merge request, it will now scroll the window down to the content.

![scroll](/uploads/c5db23e1c32b1fe62bf4efb815b3f055/scroll.gif)

Closes #15133

See merge request !4192

Also removes the note from the development/testing.md guide

Update branch name from 8-7-stable to 8-8-stable

Fix inconsistency with the command listed above.

[ci skip]

See merge request !4274

Fix typo in link on monitoring help page

Closes #17809

[ci skip]

See merge request !4281

Add CHANGELOG entry about using gitlab-shell v3.0.0



See merge request !4272