Eucalyptus: wait for an ip address

Euca instances usually return state == running before they have an IP assigned in the cloud controller. This means kitchen-ec2 gets the default (useless) IP of 0.0.0.0, and saves it.

This changes the create step to wait_for the IP to be assigned. Should be no impact on AWS, but I am fine moving this behind a new config option specific to Euca.

As far as I can tell this is the only change needed to make Eucalyptus support work.