MountService: Java.lang.NullPointerException occurs after unplug SD card.

Mediaprovider get Null pointer when Mountservice read storagelist
file. Modify implementation:
1. Mountservice register with Locale intent;
2. Receive Locale intent and read storaglist file accordingly.

Change-Id: Iafabd07ae067ab6feb0f910ab5b7b7b5b8343029
Author: Bo Huang <bo.b.huang@intel.com>
Signed-off-by: Bo Huang <bo.b.huang@intel.com>
Signed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 56843