[WIP] GitLab 6.8

**Not ready for merge**

I had a few minutes to start this today, but haven't quite finished.

Todo:
[ ] Update test suite to validate new nginx / gitlaby.yml templates
[ ] Resolve test suite errors (and_raise_error method not found on my machine; probably works elsewhere)

Passes initial smoke tests.  Check commits for additional changes recommended in upgrade file involving gzip compression.