R1:e337029769ce

Allow users to mark themselves as "Available", "Busy" or "Away" while attending an event

Summary:
Ref T11816.

- Now that we can do something meaningful with them, bring back the yellow dots for "busy".
- Default to "busy" when attending events (we could make this "busy" for short events and "away" for long events or something).
- Let users pick how to display their attending status on the event page.
- Also show which event the user is attending since I had to mess with the cache code anyway. We…