8.5 schedule fix

Fixes #418.
If you want to just flat-out delete all rows in the events table which are no longer legal, you can do the following:

```python
Event.objects.exclude(location__in=[loc for loc,desc in EVENT_LOC_OPTS]).delete()
```

Or something like that.  If you want to move them rather than delete them then it's harder (but for test data you probably don't care).