API: Change the argument of `not_found!` in `:id/repository/branches/:branch/unprotect`

not_found appends string "Not Found" to the argument causing the resulting message to be "Branch does not exist Not Found" which is an incorrect error message.

Changed the argument of not_found! for 'unprotect'  command to "Branch" from "Branch does not exist".  This makes the final error message to appear as "Branch Not Found" which is correct and same as error messages for other commands like 'protect'.

Premailer shouldn't remove script tags from our emails

Closes #14943.

See merge request !3552

[ci skip]

Closes #14943.

Fix data check in update issue response



See merge request !3548

Dropdown arrow support

When the dropdown is open, you can scroll through the list of items with the up & down arrow keys. When an item is focused, the enter triggers the click event for that row.

Closes #14455

See merge request !3385

Notes form design update

Part of #3401

See merge request !3442

[ci skip]

Attribution where it is due.

Inspired by https://news.ycombinator.com/item?id=11431969

See merge request !3546

Upgrade bundler-audit from 0.4.0 to 0.5.0

Bundler Audit can now run the `check` command with an `—update` flag to update the Ruby CVE repository before checking. This removes the need for two separate commands in GitLab CI ([source](https://github.com/rubysec/bundler-audit#synopsis)).

See the Changelog for more information: https://github.com/rubysec/bundler-audit/blob/master/ChangeLog.md#050--2015-02-28

See merge request !3433

Check permissions when importing project members

Closes #14899

See merge request !3535

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

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

Fix LDAP link and codeblock indentation



See merge request !3538

[ci skip]

Update language after doing all other operations

See merge request !3533

Added CHANGELOG for build notifications

[ci skip]

See merge request !3537

[ci skip]

Add comments to the SCSS Lint config file [ci skip]

This MR also adds some previously missing linters.

See merge request !3500

When importing members, and user does not have permissions to read
members in a source project, do not leak information about source
project existence. Notifiy user that project has not been found instead.

Add missing changelog item about improving navigation sidebar
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

For !3494 and #14838 

See merge request !3527

Closes #14899

Fix Importing repos from GHE doesn't work

See merge request !3529

Add link to image URL for images in discussions.

The main problem with this is that it doesn't apply retroactively, only to images that are uploaded after this change. It's also hacky and probably not the most optimal solution.

Resolves #14411.

See merge request !3464

Resolves #14411.

See merge request !3464

Also add some previously missing linters.

Remove 2FA status on enable page

The 2FA status on the enabling page is useless, since it always is `disabled`. A user is enabling 2FA, so he already knows that it is disabled.

### Before

![Screenshot_2016-03-29_12.41.27](/uploads/4800a13a82f176077a11ecaf13ed0cb1/Screenshot_2016-03-29_12.41.27.png)

### After
![Screenshot_2016-03-29_12.40.55](/uploads/a77e8acd7cf99190bbd6bd340542ad10/Screenshot_2016-03-29_12.40.55.png)

See merge request !3436

GitHub Pull Requests importer handle with the repository while
importing data, we need to make sure that the cached values are valid.

Improve UI for admin/groups page
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

cc @jschatz1 @skyruler 

See merge request !3523

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

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