New package: attr

Commands for Manipulating Filesystem Extended Attributes.

[Peter: needs largefile]
Signed-off-by: Heiko Zuerker <smiley73@users.sourceforge.net>
Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>