Follow the bouncing docker-registry package. Rather than use the docker hub
registry container, we can have finer grained control if we clone and build
the docker-distribution repository directly.
Since this is distinct from the main docker package/codebase, we break the
registry back out into its own package.
We also create a baseline configuration and .service file that can be the
basis for more complex implementations.
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>