Move to v3 API

[avram]

Move to V3 API and its support for better syncing and partial syncs

[judeibe]

Been looking at API 3, it supports JSON can the app implementation use that.

[avram]

Yes, it would be great to eliminate the XML handling components of the sync system-- that is an unpleasant and complex pile of code.

[judeibe]

I have started working on the code. I will create a pull request. I am using gson and retrofit.