Handle calendar sync state changes by observing Calendars; cleanup

* Use a content observer to detect changes in Calendars; we use this to
  determine whether or not sync has been turned off.  If sync is turned
  off, all events will be deleted, so we need to reset the sync key
* Make sure that all code working on Contacts also now works on Calendar
  (push, etc.)
* Remove some old crufty logging and out-of-date comments
* Addresses 2433061

Bug: 2433061
Change-Id: I6299168903fcce9bf820b72b5f6bb157d9169653
2 files changed