Docker Support

So I got following traceback when I was trying to remove the docker repository:

"traceback": "Traceback (most recent call last):\n  File \"/usr/lib/python2.6/site-packages/celery-3.1.16-py2.6.egg/celery/app/trace.py\", line 240, in trace_task\n    R = retval = fun(*args, **kwargs)\n  File \"/home/brq/jluza/rcm-pulp/server/pulp/server/async/tasks.py\", line 328, in __call__\n    return super(Task, self).__call__(*args, **kwargs)\n  File \"/usr/lib/python2.6/site-packages/celery-3.1.16-py2.6.egg/celery/app/trace.py\", line 437, in __protected_call__\n    return self.run(*args, **kwargs)\n  File \"/home/brq/jluza/rcm-pulp/server/pulp/server/tasks/repository.py\", line 41, in delete\n    manager.delete_repo(repo_id)\n  File \"/home/brq/jluza/rcm-pulp/server/pulp/server/managers/repo/cud.py\", line 286, in delete_repo\n    raise pe\nPulpExecutionException: Pulp exception occurred: PulpExecutionException\n",
"worker_name": "reserved_resource_worker-1@rcm-pulp-02-dev.app.eng.bos.redhat.com"

"error": {
    "code": "PLP0000",
    "data": {},
    "description": "Pulp exception occurred: PulpExecutionException",
    "sub_errors": [
        {
            "code": "PLP0000",
            "data": {},
            "description": "get_master_publish_dir() takes exactly 3 arguments (2 given)",
            "sub_errors": []
        }
    ]
},

suggested fix:

https://github.com/midnightercz/pulp_docker/commit/c2b7a8deda7047a5c6f676dad1d9eb092fdfd8de