Refactor database methods. See commit details for full listing of changes.

Delete all rows associated with a bracket from the brackets, rounds, games, and participation tables.

This code compiles but has not been tested yet.

We also use a separate IntentService for deletion, but should look into combining them into one service.

Convert database helper code to use singleton pattern.

Using the singleton pattern should help with the "database context leaked" warnings.

Also add in auto-updating of the bracket list when returned to from another Activity and padding was added to the bracket creation screen.