Allow configuring which interface to connect to

[zeelot]

Our AWS infrastructure only allows SSH into private IP addresses. Could we add an option to the config that allows us to specify the interface to connect to? Something along these lines would be great:

thing-ec2:
    provider: aws
    region: us-east-1
    access_key: <secret>
    secret_key: <secret>
    default_user: ubuntu
    connect_to: private_ip | private_dns | public_ip | public_dns

[burdandrei]

https://gist.github.com/burdandrei/2ba6e85e7b70d30213ea