Fix intermittent errors for redirect

Add assertion of header before checking URL redirect

Fixes: https://www.pivotaltracker.com/story/show/49712465
Merge pull request #162 from faun/fix_intermittent_failures

Fix intermittent errors for redirect
updated meetup message to SF Ruby
Merge pull request #163 from missherico/master

Change banner to say SFRuby
Use event's denormalized ends_at column to determine upcoming/past

Previously, we used 'event_sessions.ends_at', which can potentially
choose the wrong event_session for the source of ends_at.
Adding link to 'Class Breakdown' page on Org Dashboard

Includes a somewhat inauspicious and strange start to the Class Breakdown page

Adds backbone (via backbone-on-rails gem), jasmine, and a bunch of crazy .js files.
Remove reference to not-yet-existing /templates dir
Attend button now says Join the Waitlist if workshop is full