official image container.
This conforms to the official image rules to run the container with a shell
without using the --entrypoint flags.
Supports:
[o] docker run registry sh # /bin/sh
[o] docker run -v /a:/b registry /b/config.yml # /bin/registry serve /b/config.yml
[o] docker run registry # /bin/registry serve /etc/docker/config.yml
[o] docker run -ti registry -h # /bin/registry -h
[o] docker run <command> [args] # /bin/registry <command> [args]
Signed-off-by: Richard Scothern <richard.scothern@docker.com>
