Consider a setting that controls inter-node communication interface

[michaelklishin]

See rabbitmq/rabbitmq-website#1304 for the background.

There are advanced.config settings that control what port range will be used
by inter-node connections but . For setting the interface, this would require using inet:parse/1 from an Erlang shell.

Note that we already support interface names/IP addresses in rabbitmq.conf (thanks to Cuttlefish).

[michaelklishin]

Cuttlefish datatypes. The ip type is an IP:port pair which does not help us here but there is a validator defined in rabbit.schema which is good enough.