config: Report IP addr/nodename parse errors back

Corosync used to just ignore parse errors so that un-resolved names
could cause silent failures. We now always check the result from
totemip_parse() and at least print something in syslog.

There's also a little get-out here that allows you to correct
a bad node address without having to destroy and recreate the
whole link. I'm being nice to you.

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