Auto-tag (and auto submit new MR to gitlab-ce)

@jarv has this cool idea of using semantic-release to auto-tag.

The only thing is that this will require structured commit messages. This might be an issue with external contributions

It will be even better if we can automatically submit the newly tagged image as an MR to https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/ci/templates/Jobs/Deploy.gitlab-ci.yml#L2