Many many bugfix

- closes #43 
- Facebook URL field no longer manditory
- Google Calendar errors now render as a toast, instead of internal server erroring
- fix a few logical bugs for what events show up where
Further developments:  Because `self.start_time` returns a `datetime.time` instance, the `__nonzero__` method on `TimeField` never gets called.  Back to `is not None` I guess.