Backend support for news.
Functional news retrieval.
Switch to ISO-8601 DateTimes.
Track if news items are new.
Make news box look less crappy.
Frontend for creating news.
Fix sidebar scroll issue.
Emit events on session refresh.
Use HTML5 input types, misc HTML cleanup.
Announce new challenges.
Require answer for new challenges.
Merge branch 'news'

Adds new News feature allowing updates of unlocked challenges, admin
announcements, and even team-directed announcements.  Currently only polling is
supported, WebSocket support is planned for the future.

Conflicts:
	rest.py
	static/css/scoreboard.css
Bootstrap fanciness for emails.