Implement Exchange calendar sync support

What should be working:
* Events sync down from server and appear in calendar
* Recurrences and exceptions appear in calendar
* Changed events on server should be reflected in calendar
* Deletions on server should be reflected in calendar
* Push of new/changed/deleted events should work
* Changes on device are NOT synced back to server
* New, single events on device are synced back to server
  (no time zone, attendee, or recurrence support)
* Checkbox for syncing calendar added to setup flow
* System sync glue in manifest, etc.
* Bugs are to be expected
* A few unit tests; needs more

Change-Id: I7ca262eaba562ccb9d1af5b0cd948c6bac30e5dd
14 files changed