Enable notify in the master zone

Just to make sure that the slaves get notified. Slaves however
should not notify anymore.
Set more sensible timeout values

These values were way off. Especially a retry higher than TTL does
not make sense..
Make sure that the master node has slaves_names/ips set

Without the dup, it deletes the master node from the nodes.each
loop below, so it doesn't set anything..
Fix syntax error

'ipv-6-address' is not a valid IPv6 address.