Add Dockly::Docker::Registry

This class will be used to push docker images to regitries in lieu of
sending them to s3.
Add support for docker registries.
Remove the password prompt, favor an env variable
Add registries to the README.
Removed the baking of the DOCKER_REGISTRY_PASSWORD
Authentication is now optional for registries.
Now autoloading dockly modules in lieu of requires.
Generate the image either way
Don't do anything if the docker is nil.
Ensure the credentials are not nil.
Version bump 1.4.0