Move some methods to config resolver
move 'read_ip_address' to a Utils class
Use utils.get_ip_address in create server
change floating ip resolution when floating_ip and floating_ip_pool are nil
change signature of waiting_for_server_to_be_reachable
returns first IP address if there is only one
Don't fail if no floating_ip is resolved
Add LogLevel in read_ssh_info to avoid silent failures

Depends on mitchellh/vagrant#4637
Fail fast on resolve_floating_ip
Merge pull request #114 from ggiamarchi/issue55

Floating IP should not be mandatory