Convert CourseScheduleFragment and ExamScheduleFragment to use newInstance
pattern.

Also fix a minor typo in ExamScheduleFragment.
Clean up ScheduleActivity. Mostly removing ancient commented code.
Correctly handle loading multiple class listings. Prevents buggy behavior
such as loading multiple copies of the same class listing from happening.

Honestly, this is still being done terribly. I definitely should not be
accessing a parent activity's state from a fragment in such a clunky way.
I should be parsing part of the page in the parent activity, and then
spawning more fragments from there as necessary.  But hey, it works :)