Port the docker driver to docker-py and remove custom client code

For simplicity and ease of maintenance, remove the custom REST client
code and imports docker-py.

Co-Authored-By: Eric Windisch <ewindisch@docker.com>
Change-Id: I3e17924b8319720ceb7cee480a81e953b809d0ee
Merge "Port the docker driver to docker-py and remove custom client code"