Added ActionBarSherlock, Navigation Drawer, Integrated Index application, Implemented gmail login

Converted required activities to fragments for better integration of Navigation Drawer.
Moved old Home screen menu to Navigation Drawer. 
Index application is the new default screen after login. 
Gmail login uses oauth2 token obtained using google play services.
Additional external dependencies:
1. ActionBarSherlock
2. Google Play Services
This line here gives the NewApi lint warning: 
https://github.com/gitanshu/privly-android/blob/master/src/ly/priv/mobile/Index.java#L93
though we have already a condition in place on L92.

Maybe I should move the SuppressLint to the method instead of the whole class.