Don't copy libz and liblzo2 twice to the initrd

Signed-off-by: Shea Levy <shea@shealevy.com>
btrfs: btrfsck is now actually the same binary as "btrfs"
symlinked to save space.

Also, removed the hard-coded version-numbers for libz and liblzo.
If they get upgraded and btrfs breaks, either btrfs' build will break,
or the initrd test will anyway.
filesystems: add priority option for swap devices.

Useful for setting up raid0-like load balancing for swap.
By giving multiple swap devices the same prio.
kde4: use udisks2 for kde 4.10+