Support hot-swapping of external devices

:Release Notes:

:Detailed Notes:
Notify ShardEngine about attaching/detaching of MediaStick.
Set filter for media types. Use only "usb" media

:Testing Performed:

:QA Notes:

:Issues Addressed:
[GF-3563] DB8 Ext: Support hot-swapping of removable database

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

Change-Id: I950445e4ebcefa775e33984bfa3044c9511b18d5
Reviewed-on: https://g2g.palm.com/3194
Reviewed-by: Build Verification
Reviewed-by: Roger Stringer <roger.stringer@lge.com>
Tested-by: Roger Stringer <roger.stringer@lge.com>