Local network module

[rebeccaskinner]

We should have a module (or modules) to support configuration of local networking. The basic version would be something like:

network.interface {
  device = "eth0"
  address = "10.10.9.9"
  subnet = "255.255.0.0"
  gateway = "10.10.1.1"
}

We could also support
address = "10.10.9.9/16" or dhcp = true

It probably doesn't make sense to support wifi here