This commit includes the major changes between DAVdroid and EteSync. It
adjusts the app to use the EteSync protocol and server. It includes some
ugliness still, and it's a squash of many ugly snapshot commits while
hacking on the initial DAVdroid code.
History should be "clean" from this point onwards.
* resource detection is subject to change yet
* don't use UID_2445 for Android <= 4.1
* more useful sync error notification messages
* handle 401 Unauthorized and show account info when notification is tapped