Add status for registerMedia method

:Release Notes:
Methos registerMedia will return status for caller.

:Detailed Notes:

:Testing Performed:
tested on local build

:QA Notes:

:Issues Addressed:
[ANG-966] [Boottime] DB8 should not call cbox in boottime
[BHV-3659] [CBOX]: Notify DB8 about attached/detached media

Open-webOS-DCO-1.0-Signed-off-by: Igor Kuksyuk <igor.kuksiuk@lge.com>

Change-Id: I9d65f697ccd826c3cf5c4b34c1e136610a265294
Reviewed-on: https://g2g.palm.com/5476
Reviewed-by: DCO Verification
Reviewed-by: Oleg Yablokov <oleg.yablokov@lge.com>
Tested-by: Igor Kuksyuk <igor.kuksiuk@lge.com>
Reviewed-by: Igor Kuksyuk <igor.kuksiuk@lge.com>