Add ability to create branch in Gitlab

The current integration is nice, but IMHO the wrong way arround.

It would be way more usefulle is IMHO that one should be able to create a branch in gitlab directly from trello. And in the common case this branch will get to a Merge Request in the future, means it would be really nice to have an automatic tracking.

With automatic tracking i mean that if i create a branch from trello and this branch is later submitted as a merge request the status in trello should automatically update and reflect that (including showing of CI/CD status of either the last commit in the branch OR of the Merge Request if one is in Progress).

Automatic mapping of states in gitlab, eg. WIP in gitlab to automatic lable in trello would also be awesome.