quorumtool: Sort output by nodeid

corosync-quorumtool prints the node listing by IP address
(as passed back to it from corosync) but this can be
counter-intuitive if the node IDs aren't in the same
order as the IP addresses. This patch sorts the nodes
by node ID so that the output is easier for humans to
parse.

Signed-off-by: Christine Caulfield <ccaulfie@redhat.com>
Reviewed-By: Jan Friesse <jfriesse@redhat.com>