Changes related Sync Engine library that communicates to cloud server

This change updates some of the code that the library uses
to communicate with the cloud server
Specifically :
- Update BlockingHttpClient to use template ResponseProcessor
- Update HttpUrlConnectionBuilder to setAuthToken for HttpUrlConnection

Bug: 17464069
Bug: 17464805

Change-Id: I7d7b58dff594b920162f799d102e8582ff9fe6a4