Remove emphasis from system notes to avoid Markdown conflicts in names.

Changes:
- change `.navbar-toggle` from `margin: 0 -15px 0 0;` to `margin: 0;`

This reverts commit c42262b4, reversing
changes made to c6586b12.

Fixes issues #880, #723, #1113: Markdown must be rendered to XHTML, not HTML, when generating summary content for Atom feeds. Otherwise, content-less tags like <img> and <hr>, generated when issue descriptions, merge request descriptions, comments, or commit messages use emoji, horizontal rules, or images, are not terminated and make the Atom XML invalid.

Use more restrictive permissions for backup tar files and for the db,
uploads, and repositories directories inside the tar files.

This reverts commit 07f9a3f9, reversing
changes made to 48036751.

Reverted this because the data is used in hooks as well.

Remove unnecessary fetch of commit messages for initial push. This will reduce the memory usage significantly.

It is same search like we have at issues page. It allows to quickly
filter merge requests based on title or desription. I copy-pasted some
js code from Issues.js. In future search (filtering) logic should be
refactoed into one class for merge requests and issues