Initial xattr support

setting the attributes through the extended file-attributes avoids problems with self-checking executables (e.g. skype) and file integrity scanner like tripwire.
This patch only allows to set all flags with setfattr, we still need to figure out a way to set them only on specific files.
Note that some more "exotic" file systems don't support xattr (aufs for example).

Signed-off-by: Lukas Reuter <lukas.reuter.lr@gmail.com>