Figure out user story to gain access to one's GitLab account

For #69 (closed) I have to document how a user can gain access to their shinny new GitLab account.

So far we've assumed that setting correct email addresses (#34 (closed)) was enough, but I don't know that we've tested it. In particular, there's the whole unverified/unconfirmed email address business, that might get in the way.

I think we need a plan.