Making the git back end production ready

[reidka]

The biggest problem so far is performance. I'm not sure whether we can fix this.

1. A nice warning pops up when you click on the Create All Groups button in the groups view. If I refresh the page the warning goes away, even when it is still processing. We really need a way to see whether all groups have been created.
2. Loading the the Submissions view is painfully slow. It took close to 2 minutes to load 214 submission (vagrant box on my mac).
3. Students don't see the correct repository path in when submits using version control checked.
4. When I create repos using "Create All Groups" the permissions aren't set properly in .gitolite/conf/gitolite.conf (git user) Git backend: permissions not set for Create All Groups #2674

[KR: I'm going to keep adding to this issue, and probably break it up into smaller issues, so it isn't complete yet.]