Nudge users to close their question if it's been answered

Summary: Adds a notice reminding viewers of their own question to resolve it and mark the correct answer.

Test Plan:
View my own open question, see notice. Resolve question, notice goes away.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D13958