This is needed so that we can have encrypted storage and complex keys
(e.g. multiple CA certs). Multiple CA certs are needed for an in-place
upgrade from kube-up v1.
* GCE support only
* Key and secret generation
* "Direct mode" makes API calls
* "Dry run mode" previews the changes
* Terraform output (though key generation not working for master ip)
* cloud-init output (though debian image does not ship with cloud-init)