Cleaner Docker::Image.save_stream spec
Cleaner Docker::Image.save_stream spec

Instead of checking the entire tar contents, it just checks that there
are the same files.

ComputeStacks/docker-api,someara/docker-api,moritzheiber/docker-api,ComputeStacks/docker-api,someara/docker-api,swipely/docker-api,moritzheiber/docker-api,swipely/docker-api