[arm-allstar] block un-wanted node number

[Carlos Crespo]

A while back I needed to permanently block a node in a hurry. I was not
aware of the blacklist feature so I wrote a node entry in rpt.conf to
permanently route the offending node to a local, none existing, subnet. I
other words, map the offending node to a fake local IP.

4#### = radio at 192.168.ABC.XYZ/4####,NONE