New calendar sync adapter tests

* Created MockProvider that can be used for testing the results of
  ContentProviderOperation's for Calendar/Contacts (we can't use these
  within our mock contexts because we can't instantiate the provider
  classes within the Email package)
* Wrote some unit tests for MockProvider
* Use MockProvider to test addEvent, in particular how a user's attendee
  status is stored, depending on whether the event is new or updated

Change-Id: I97f02d125eb7347726261e12ce70aadc539be1d4
5 files changed