Import the database as the `git` user

This ensures that all tables created during the import belong to `git`.
If you import as a different user, such as the `postgres` superuser, you
may encounter issues where the GitLab database user cannot access tables
in gitlabhq_production, _even if_ `git` is the owner of
gitlabhq_production at the time of import.
Update markdown reference to external issues

1. Issue may be not only in jira.
2. Rewrite method for support different external issue trackers
Delete mailer queue because we don't use sidekiq_mailer gem and now the mailer queue doesn't exist any more.
change bash to sh
fix bash-ism
Fix missing links and incorrect display of issue numbers for notes, comments, and merge requests
Moved padding from li to a in dashboard groups / projects listing
Removed redundant spans
Remove duplicated setupNoteForm method
Add dealing with newlines for editor to 5.1-to-6.0

backport of https://github.com/gitlabhq/gitlabhq/commit/2d681c0d1ed14bf23c041aa04fa3e77caceda9a1
Add, delete labels via API
Update labels via API
Update gemnasium-gitlab-service
Update org-ruby
Disable label submit button if any field is empty
Move label coffeescript from view to class
Add testcase for invalid color
Labels need to be valid on name
Validate label titel in project scope
Trigger an update of save button if user pressed a preview color