TestEnv improvements

Affix milestone/assignee UI element

See merge request !1536

Remove Group#owner_id from API

For #1943

See merge request !1537

Hide Gitlab.com import for GitLab.com

See merge request !1538

Add new style to "New group" button

Bump gitlab shell

See merge request !1535

Make sure Markdown previews always use the same styling as the eventual destination.

Font size, image width and code-block styling weren't accurate between the markdown preview and the issue/wiki/note body.

See merge request !1514

The new group button style was changed to have the same look as the new
project button (green background).

Fix broken access control for note attachments

From https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/332 by Hannes Rosenögger.

See merge request !1528

Highlight bugfix

Fixes:

* snippet rendering bug #2011
* dev fixtures has invalid root user

See merge request !1532

Updated guides for 7.8

Updated guides fro the 7.8 release

Fixes #2009

See merge request !1531

- Simplify cleaning the temporary testing path in TestEnv
- Don't run gitlab:shell:install if it's already installed
- Run git commands quietly

Fix duplicate authorized applications

On the profile applications page, display one row per authorized app instead of one row per access token.  See #1987.

cc @sytse

See merge request !1524

Remove top margin for issue/mr title

See merge request !1529

Fix double note submit

Closes #1989.

See merge request !1527

This commit moves the note folder from
/public/uploads/note
to
/uploads/note
and changes the uploader accordingly.
Now it's no longer possible to avoid the access control by modifing the url.
The Avatar upload has been refactored to use an own uploader as well
to cleanly seperate the two upload types.

Rephrasing in documentation for manual installs

Rephrased the wording in the documentation to say "installation from source" or similar.

/cc @sytse

See merge request !1526

Rephrased wording in the documentation to say "installation from source" instead of  "manual installation" or similar.

Fix typo in changelog

Fixed small typo in changelog file.

Only send "Account was created for you" email when created by admin.

See #1985

cc @sytse

See merge request !1517

Add links to the quick help list

Add links in the quick help list to the pricing and feature comparison pages on about.gitlab.com.  See #1969

cc @sytse

See merge request !1525