Transition to SQLite database (many changes)
-MainActivity and PollService now access events through DatabaseInterface
-DatabaseInterface provides an abstracted interface to EventProvider
-EventProvider exposes the local SQLite database of calendar events
-many changes, events in MainActivity can have specific ringer types set
-each calendar event is tied to a specific instance.  This means that reoccuring events can have different ringers for each occurance
-blank icon is used to indicate that the event has no specific ringer set and that default will be used
-tap event to cycle ringer types
-long press event to reset to default ringer

Known Bugs
-trailing buffer seems to be ignored
-icons need to be updated