new feature: live registration updates

Live registration updates. You sit on a page and (with a 1 minute lag for caching/performance reasons) get realtime notifications when people register to attend the event.

It also plays a sound : )

Really this was a test of setting up pyCharm debugging/server stuff before getting more serious about diving in on the heavier features.  But it's pretty cool.

There's a bunch of generic junk in the .idea folder that I think is probably useful for other people using PyCharm, which we'll hopefully be getting other users more serious about.  One less thing to configure.  Don't bother to code review any of the .idea stuff except to make sure it doesn't have stuff like secret keys/etc in there.

I also added the Moment JS library which is a lot newer/better maintained than the Date.js wrapper we're currently using.  I think it might be in angular also, not sure.