Remove the networ_interface parameter in nomad config
This means that nomad will now autodetect its own ip address
by looking at the default route.
Thus nodes in a LAN behind a NAT will get their LAN address,
and internet nodes will get their public address.
They won't get their VPN addresses.
This seems not to break Consul's use of VPN addresses to address
services, and fixes attr.unique.network.ip-address for DiploNAT.