Project destroy relationship speed fix

Removes destroy callback for users_projects when a project is destroyed.
This works okay becaues the gitolite config will be updated at at the
end to remove the entry entirely, thereby removing the users anyway.

Bulk repo import Rake task

Merge requests in dashboard state indication

Image is broken on dashboard if deployed to a subdomain

Conflicts:
	app/views/refs/_tree.html.haml

Git repos should be in the import_projects directory in the root of
application. The task is invoked via @rake import_projects@.