More work on selecting individual calendars to sync
-renamed CalEvent to SimpleCalendarEvent, moved to database package
-renamed Calendar to SimpleCalendar

CalendarsActivity:
-implemented listeners for cancel button, sync all calendars switch
-ok button restarts service

Prefs:
-implemented setSyncAllCalendars(), shouldAllCalendarsBeSynced()
-setselectedCalendars() now clears preference to sync all calendars

EventSilencerService:
-shouldEventSilence() now checks if the active event is in one of the calendars set to be synced