Show Open/Closed Status on Issue Mention

This issue continues on https://gitlab.com/gitlab-org/gitlab-ce/issues/20934

Basically it adds the context of the issue status (open or closed) to an issue mention, so they will look like:

#20934 [closed]

#20934 (comment 13898609) [closed]

Brackets seemed the best fit

cc: @jschatz1 @dzaporozhets @JobV @undefined

related issues:

• https://gitlab.com/gitlab-org/gitlab-ce/issues/20948
• https://gitlab.com/gitlab-org/gitlab-ce/issues/21179

mentioned in issue #20934 (closed)

can we get this to front-end?

mentioned in issue #20948 (closed)

@dimitrieh There is already a very old issue about that: #1369 (closed) I considered working on that one.

closing this in favor of https://gitlab.com/gitlab-org/gitlab-ce/issues/1369#note_14400430

Status changed to closed

mentioned in issue #1369 (closed)