FileUtils: add method to get UUID of a volume

Change-Id: I41b76c5e01c82a2f8e67b33133a76947877a2814
Fix requery behaviour of MemoryCursor.

As we can't restore the contents of the cursor window, we need to keep
it on deactivation so we can restore it on requery().

Change-Id: I06f688bbe9120c307bdc3ddbc3833416becdec82
Merge "FileUtils: add method to get UUID of a volume" into cm-10.1
Merge "Fix requery behaviour of MemoryCursor." into cm-10.1
Merge remote-tracking branch 'upstream/cm-10.1' into HEAD