unionfs-fuse: A FUSE based implementation of UnionFS

Cc: Koen Kooi <koen@dominion.thruhere.net>
Cc: Philip Balister <philip@balister.org>
Cc: hongxu jia <hongxu.jia@windriver.com>
Signed-off-by: Tom Rini <tom.rini@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>