MAP: Add following conditional checks from MAPServer :

- Track registration and unregistration for BroadcastReceiver
  through a instancee flag to avoid illegalArg and null pointer
  execption. This useecase is hit when onStop() for MAPService
  is triggered  without onStart() being triggered for shutdown
  process is invoked even before MAP profile is actually started.

- Avoid running contentobserver for SMS/MMS instance on
  main thread looper to  fix ANR reported while handling
  content changes for SMS and MMS listing.

- For GETMessagesLisitng  ensure blank subject string is
  set to include this mandatory feild and handle possible
  "null" value fetched from db.

CRs-Fixed: 963374

Change-Id: I8a1d3524784ec3942b962992059a1678d3b74d1e