Show fuller code quality notices inside the MR widget

Issue idea came from: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1984#note_31097686

It will need https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1984 to be finished first

Proposal

Related issues

https://gitlab.com/gitlab-org/gitlab-ce/issues/4044

CC/Call to actions

@markpundsack @joshlambert @bikebilly @dzaporozhets