Dockerfile and container running

My code might not be truly clear, but ...
I added a Dockerfile to generate an image that can be run on a docker host to backup restore data volume containers.

I had to change a few things, such as transforming the call to docker client when restoring to using docker-py module ... and recoding for that matter the volumes_from ... in order to add the correct tar path binding ;)

a few documentation/help and checks also included.

It still runs fine out of a container I made sure of this.

From what I see, it's running smoothly.
Hope you'll like it ;)