Fix for luna-sysservice getPreferences() bug

 :Release Notes
 The subscribed flag added in return statement.

 :Detailed Notes

 :Testing Performed
 Compiled locally and tested in device.

 :QA Notes

 :Issues Addressed
 [GF-13470] com.palm.systemservice doesn't respond with "subscribed: true"

Open-webOS-DCO-1.0-Signed-off-by: Yasaswini A Y <yasaswini.ay@lge.com>

Change-Id: I4c16048a80f043b039391db08a80661f756101cf
Reviewed-on: https://g2g.palm.com/3134
Reviewed-by: Yasaswini AY <yasaswini.ay@lge.com>
Tested-by: Yasaswini AY <yasaswini.ay@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Roger Stringer <roger.stringer@lge.com>