refresh ec2 hostname/ip from server id 

This change will refresh the EC2 instance hostname/ip immediately prior to the first ssh connection setup for the driver lifetime.

I see test-kitchen used in 2 complementary ways - full CI on the one hand, and developer converge/verify hacking on the other. This change is targeted at the latter. 

The change solves a problem where (to save $$$) the developer stop the EC2 instance before going home and start it again in the morning to resume work. Because EC2 assigns a new public ip when the instance is restarted, it would break kitchen-ec2 because the public ip stored in the state file would never be updated. 

This change doesn't fix the state file not being updated - so 'kitchen diagnose' will show incorrect information. Fixing this would need a change to test-kitchen/test-kitchen.