'Retrieve the given device
Args:
user_id (str):
device_id (str):
Returns:
defer.Deferred: dict[str, X]: info on the device
Raises:
errors.NotFoundError: if the device was not found'

@defer.inlineCallbacks
def get_device(self, user_id, device_id):

    try:
        device = (yield self.store.get_device(user_id, device_id))
    except errors.StoreError:
        raise errors.NotFoundError
    ips = (yield self.store.get_last_client_ip_by_device(user_id, device_id))
    _update_device_from_client_ips(device, ips)
    defer.returnValue(device)
