Make sure we checkout a git repo

In the current situation the tests are failing because of the missing git repo, I added the gitlab-test repo (https://gitlab.com/gitlab-org/gitlab-test) to bin/setup so that we have a repo to test against.

In this PR there is no real testing against the repo (for the ranking part). Since we need to figure out what the contributors to that repo were at a certain point in time.

another way we can tackle this, use the actual rails git repo to check against, and keep the codebase as much the same as the original Rails one. This has not my preference, since that will not allow us to make it our own.

Depends on !3 (merged) /cc @rymai