remove roundtrip timeout
remove roundtrip timeout

this doesn't allow the longer (30s) dial timeouts to be hit.

don't think this was ever actually needed.
concourse/docker-image-resource,barthy1/docker-image-resource,SillyMoo/docker-image-resource,barthy1/docker-image-resource,SillyMoo/docker-image-resource,ggeorgiev/docker-image-resource,concourse/docker-image-resource,ggeorgiev/docker-image-resource