Remove arakoon node info from the voldrv config

[wimpers]

Currently the config contains sections like

"volume_registry": {
        "vregistry_arakoon_cluster_id": "voldrv",
        "vregistry_arakoon_cluster_nodes": [
            {
                "host": "10.100.188.32",
                "node_id": "7YOsswpaYqrXivNV",
                "port": 26416
            },
            {
                "host": "10.100.188.33",
                "node_id": "FLWtBwcNfZPudBsr",
                "port": 26416
            },
            {
                "host": "10.100.188.31",
                "node_id": "wPkwuNUhSQ5fHQro",
                "port": 26416
            }
        ]

if the arakoon node config changes we need to update these sections. Better would be to only store the arakoon cluster id and get the arakoon config from the distributed config mgmt arakoon.

Same goes for "events_amqp_routing_key": "volumerouter"