AI 143181: am: CL 142924 Support DCM specific MMI network service.

  IExtendedNetworkService has 4 MMI service interface used by PhoneUtils to put DCM related nw service.
  void setMmiString(String number);
  CharSequence getMmiRunningText();
  CharSequence getUserMessage(CharSequence text);
  void clearMmiString();
  And the service is bind via "com.android.ussd.IExtendedNetworkService".
  Original author: johnwang
  Merged from: //branches/cupcake/...

Automated import of CL 143181