Add some running code for lidar cache, test stubs, fix proto.

car/tests/test_lidar_cache.py

@@ -0,0 +1,10 @@
+import unittest
+import car.tracking as tracking
+
+class TestLidarCache(unittest.TestCase):
+    
+    def test_fake_scanner(self):
+        pass
+
+if __name__ == '__main__':
+    unittest.main()