Convert control loop tests over to simulated event loop

This makes it so that we properly only use ShmEventLoop for running in
realtime on a robot.  Very nice.

Change-Id: I46b770b336f59e08cfaf28511b3bd5689f72fff1
diff --git a/aos/util/log_interval.h b/aos/util/log_interval.h
index 69170e4..acd32e8 100644
--- a/aos/util/log_interval.h
+++ b/aos/util/log_interval.h
@@ -28,6 +28,7 @@
 
   void WantToLog() {
     if (count_ == 0) {
+      // TODO(austin): event loops!
       last_done_ = ::aos::monotonic_clock::now();
     }
     ++count_;