Allow nested repositories

[buschtoens]

GitLab supports arbitrarily deeply nested sub-groups, meaning that remote URLs like git@git.devrepo.ddg:web/frontend/app.git, where web/frontend is the project and app is the repo are valid.

The regex in RemoteRevision.js#parseProjectAndRepo does not support that. Adding a third variable, the full repo path (web/frontend/app in this example), would suffice for supporting GitLab.

Are you up for a PR?

[alexcorre]

@buschtoens definitely up for a PR to support this feature