From now on magnum had container create and delete api .The container create
api will pull docker image from docker-registry.But the container delete api
didn't delete image.It will let the image remain even though didn't had
container use it.Is it much better we can clear the image in
Interesting topic, pulling image is time consuming, so someone might not
want to delete the container; But for some cases, if the image was not
used, then it is better to remove them from disk to release space. You may
want to send out an email to [openstack][magnum] ML to get more feedback ;-)
