Bug 1054437 get involved redesign

Probably needs a bit more polishing and tidying but it's complete enough to start code review.

Run <code>./manage.py cron update_reps_ical</code> to fetch events if you don't already have them.
This was pasted from somewhere else, and actually I'm not changing the styling of the hamburger between open and closed so we don't need this at all. Removing.