Change the way the consensus is received

Currently it receives the new consensuses using https://stem.torproject.org/api/control.html#stem.control.Controller.get_network_statuses, which uses the cached-consensus and might not be updated. It should probably receive the new consensuses as soon as they arrive using an event listener https://stem.torproject.org/api/control.html#stem.control.Controller.add_event_listener, instead of every x time.