Add a route to the gateway when hosted on a different subnet

  use case: a number of dedicated server providers offer failover
  ips. In that case the gateway that needs to be used is the server
  main ip address which is usually hosted on another subnet.

  see for instance (section 2.4) :
	http://forum.online.net/index.php?/topic/4437-all-about-failover-ips-beginners-guide/