metadata: Populate CloudSigma's IPs properly

There are no CloudSigma networking specifics when it comes to private networks. 

And I'm still not sure how to check if dhcp has finished. Also, what if the machine is configured to NOT use dhcp? Then this `isAvailable` check will always fail.

@crawford, since you're far more familiar than me with CoreOS, could you please give an example how to make that check using just the mechanisms provided by CoreOS?

The only way I found was to check if there are files in `/run/systemd/netif/leases/`. But can I rely on that? Is it generally a good idea to do that?