Implement Handling of PDM messages

:Release Notes:
Add ability to receive notificationss about attaching/detaching media
from the attachedstoragemanager, if it is supported on the platform.

:Detailed Notes:

:Testing Performed:

:QA Notes:
This is currently complied with PDM support suppressed.  To validate
PDM support, edit src/db-luna/MojDbLunaserviceApp.cpp line 55+- to
set m_pdmEnabled to true.

:Issues Addressed:
[GF-12007] DB8 Ext: Subscribe for notifications from PDM

Open-webOS-DCO-1.0-Signed-off-by: Maksym Sditanov <maxim.sditanov@lge.com>

Change-Id: Idd51263afd280bda25471b4cc10f74f39a99d34c
Reviewed-on: https://g2g.palm.com/3117
Reviewed-by: Build Verification
Reviewed-by: Roger Stringer <roger.stringer@lge.com>
Tested-by: Roger Stringer <roger.stringer@lge.com>