When checking if url is GitLab proof, check if it points to a
gitlab_proof repo instad of the gitlab.com domain. This way self hosted
instances could be added.
Also go back to searching for user first and then for the repo since
repo search is unreliable.
I've just hacked up a simple solution for GitLab proof. It's using a
project (repository) as a proof method since it's the easiest to do with
api. It's a very hacky solution and it relies on GitLab being able to
find the project using search.
