node.xml: fix partitioning for node with 1 disk
node.xml: properly set permission to /dev/zfs

udev cache rules with GID at boot times so if the group is not
defined when the machine boot it will never be applyed properly

For this reason we need to touch the file containing the rule
so udevd will reload the group->GID association for that rule
After that the udevadm trigger will do its job and set the
permissions properly

1 day to debug this :-(