zfs task cleanup

Put the zfs, ztest, zdb and zpool binaries in ../bin so that they get
patchelf'd by the initrd builder

Move restartIfChanged attribute to where it is being heeded.

Ignore failures in zfs mount, and zpool imports.

Make zpool import wanted by the filesystem target, otherwise it might
not happen.
zfs does not work with less than 768M of memory
support zfs in the iso
ztest seems to expose some bugs in writeback mode
tweak swap zvol for lower memory

Remove caching and compression on the zvol used for swap, in the event
of a low memory condition, this means less chance of an expensive RMW
.