Fixed MediaScan Issue w/ Directories

MediaScan wasn't being done recursively, so moving a directory which
had content to a different location wouldn't include the children
in the scan. This implementation makes sure all files and folders
within the directory are also scanned.  Tested against a dataset of
1000 videos, so performance seems fine.

Cherry-Pick: 037d6356
Ticket: QRDL-1009

Conflicts:
	src/com/cyanogenmod/filemanager/util/CommandHelper.java

Change-Id: I1c0d33dca262e4215f5a41a9fc2e57196d6396d2