Implemented notifications for restaurant and user updates
Added device token to endpointArn mapping
Added regId to endpoint Arn mapping in GCMDataStore
Refactored APN and GCM register/unregister code
Refactored APN and GCM register/unregister code
Refactored APN and GCM register/unregister code
Removed unused Amazon sample code
Delete endpoint arn and remove device mapping on unregister for both APN and GCM
Updated README