Rework lidar to better support testing and listeners.

tracking/lidar_servicer.py

@@ -2,6 +2,7 @@ import tracking.lidar_tracker_pb2 as lidar_tracker_pb2
 from tracking.lidar_tracker_pb2_grpc import PersonTrackingServicer
 from tracking.lidar_cache import LidarCache
 from multiprocessing import Process
+import Messaging.message_factory as mf
 
 
 class LidarServicer(PersonTrackingServicer):
@@ -19,4 +20,4 @@ class LidarServicer(PersonTrackingServicer):
         '''
         Starts the lidar cache. 
         '''
-        self.cache.start_cache()
+        self.cache.start_cache(mf.getZmqPubSubStreamer(request.value))