The GitLab API is totally broken with pagination, but if users have a large

number of repositories which are separated into groups, we can do a better job.
This change is based on John Earl's code at /r/5789/ but I've made some

changes to keep things a bit more concise, added a separate error for when the

group name is incorrect, and added and fixed unit tests for everything.

The original change listed that the groups iteration code was tested against

  a large GitLab installation in both the devserver and production.
Ran unit tests.