Add links to GitLab CI dashboards

[mvandenburgh]

@zackgalbreath I didn't have permissions to make changes to your branch in #48, so I just pushed a new one. This is what this looks like:

[mvandenburgh]

Hmm @zackgalbreath you're not showing up in the reviewers list for me. So, take this comment as a review request :slightly_smiling_face:

[zackgalbreath]

LGTM