Add an API endpoint for pushes from Gitlab

Does anyone have any thoughts on this being implemented like this? There is still a TODO, as well as testing, but the idea is solidified.

I understand that "Do not merge pull requests are an anti-pattern", so if there is a more appropriate place to put this code, just let me know, but as it stands, I think this is the only way to get ideas and initial implementations reviewed (as we have no mailing list for this project, etc).