Add basic Gerrit support to git-repo
git-repo is a git client tool that supports project management systems that include git projects, such as GitHub , GitLab, BitBucket, etc.
It has a simpler and consistent interface for working with them all, such as
git-repo <target> request create to submit a patch for review, and
git-repo <target> request fetch <id> to fetch a patch for review.
It does not yet understand git projects that use Gerrit.
This task is to create a basic
git-repo backend which can clone a repository hosted on Gerrit, concretely by creating a file in services/ext dir.
See also this issue upstream : https://github.com/guyzmo/git-repo/issues/19