Fixes #7617 - CRUD docker repo bindings

Added docker repo bindings to runcible
Includes CRUD for docker repo related operations along the same lines of puppet
and yum repo types.
Fixes #7765 - Add docker methods to repo
Merge pull request #129 from daviddavis/docker

Fixes #7765 - Add docker methods to repo
Merge pull request #130 from Katello/docker

Docker Bindings to Runcible