Added two functions to scheduler.Event: event_type and event_type_name
These will return the underlying (conference) type for some scheduler
event, or the name of that type.

Usage example:
>>> all_events = list(sched.Event.objects.all())
>>> [event.event_type for event in all_events]
[<class 'gbe.models.Show'>, <class 'gbe.models.Show'>, <class 'gbe.models.Show'>, <class 'gbe.models.Show'>, <class 'gbe.models.GenericEvent'>, <class 'gbe.models.Class'>, <class 'gbe.models.Class'>, <class 'gbe.models.Class'>, <class 'gbe.models.GenericEvent'>, <class 'gbe.models.GenericEvent'>, <class 'gbe.models.GenericEvent'>, <class 'gbe.models.GenericEvent'>]
>>> [event.event_type_name for event in all_events]
['Show', 'Show', 'Show', 'Show', 'GenericEvent', 'Class', 'Class', 'Class', 'GenericEvent', 'GenericEvent', 'GenericEvent', 'GenericEvent']

This may be useful.