Telephony plugin for GsmServiceStateTracker

 - Add makeGsmServiceStateTracker method in TelephonyPlugin
      to have  provision of extending it from proprietary space.
 - Added telephony delegate function and created QtiGsmServiceStateTracker
   in proprietary jar file

Change-Id: If048d14a4cc614e34afdbe1e1bf41023702a5cb1
CRs-Fixed: 902503