Tweak tab spacing in Ajax module code
Fix errors resulting from nonexistent event types

The teacher events module was calling EventType.objects.get() with event
descriptions that didn't exist, so I changed it to get_or_create().
Fix some errors in Ajax UI filtering tests

There were some issues stemming from trying to use filtering widgets when
the class directory (instead of the filtering options) was being shown.
To correct this, the filter_directory() function makes sure to click the
accordion header for the filtering options before trying to change
filtering options.
Clear possible merge mistake in esp/program/tests.py
Remove partial comment in scheduling.css