Added EventManager to handle getting best ringer for a given event
-renamed SimpleCalendarEvent to EventInstance
-renamed SimpleCalendar to Calendar

EventSilencerService:
-replaced call to getHighestPriorityRingerForEvent() with instance of EventManager

EventCursorAdapter:
-getRingerIcon() updated to use EventManager
Changed ringer definitions to an enum
-added RingerType to hold enumerated ringer values
-multiple updates across the board to use RingerType during runtime, int values when writing to database or shared preferences
Bugfixes, finishing transition to enumerated ringer types
-changed colors used to indicate ringer source (using some temporary colors from the material design color pallet)

EventManager:
-added getRingerSource() to simplify finding where an events best ringer came from

EventDetailsFragment:
-uses EventManager now

MainActivity:
-uses event manager to get events ringer source
-fixed bug where ringer icon color was not being applied correctly

SelectCalendarsActivity:
-selecting a ringer type while configuring a calendar now immediately applies the change (OK and Cancel buttons only close dialog now)

RingerSource:
-added enum types to represent where an events ringer was set

RingerType:
-added getIntForStringValue() to get the integer value of a ringer type to match the given string

Prefs:
-fixed bug in getRingerType() that would result in an exception being thrown if an unknown integer value had been stored.  Now uses DefaultPrefs' RINGER_TYPE