Queue args

Addresses issue #19
Deployments now have a queue_arguments dict which will be passed to each Queue on creation. If you need and 'x-ha-policy' of 'all' your deployment config would look like this:
{"deployments": [
    {   
        "name": "east_coast.prod.global",
        "durable_queue": false,
        "rabbit_host": "10.0.0.1",
        "rabbit_port": 5672,
        "rabbit_userid": "rabbit",
        "rabbit_password": "rabbit",
        "rabbit_virtual_host": "/",
        "queue_arguments": {
            "x-ha-policy": "all"
        }
    }]
}

Also, Introduces some worker unit tests.