Added contract classes and schema information for meetings table.
Migrated ScheduleFragment from a ListView to an ExpandableListView for a nested ListView alternative. A TreeCursorAdapter was similarly implemented to back the ListView.
Meetings data now loads into the ScheduleFragment's ExpandibleList (without visuals).

Moved CoursesTreeCursorAdapter into an inner class of ScheduleFragment and added support for loading
meetings data for each group entry in the adapter.

Updated schema and meeting's model to better integrate with the CursorAdapter and loading.