Convert BallDetector to event loops.

Change-Id: Ic2716e5cc6d2573835aa039ce50d1ed96c882eed
diff --git a/y2016/queues/ball_detector.q b/y2016/queues/ball_detector.q
index 948cc25..9dc686f 100644
--- a/y2016/queues/ball_detector.q
+++ b/y2016/queues/ball_detector.q
@@ -1,5 +1,6 @@
 package y2016.sensors;
 
+// Published on ".y2016.sensors.ball_detector"
 message BallDetector {
   // Voltage measured by the ball detector sensor.
 
@@ -10,4 +11,3 @@
 
   double voltage;
 };
-queue BallDetector ball_detector;