Check against actual superstructure voltage limits

The superstructure uses 5V when "slow moving". Someone added checks
against a hard-coded 4V though so two tests were causing the test
binary to crash.

Change-Id: I32c4a1e0b1c26bcd9ef66e5d503fe780e2fd316a
diff --git a/y2016/control_loops/superstructure/superstructure.h b/y2016/control_loops/superstructure/superstructure.h
index 2967a72..d922972 100644
--- a/y2016/control_loops/superstructure/superstructure.h
+++ b/y2016/control_loops/superstructure/superstructure.h
@@ -101,6 +101,9 @@
       control_loops::SuperstructureQueue *my_superstructure =
           &control_loops::superstructure_queue);
 
+  static constexpr double kZeroingVoltage = 5.0;
+  static constexpr double kOperatingVoltage = 12.0;
+
   // This is the angle above which we will do a HIGH_ARM_ZERO, and below which
   // we will do a LOW_ARM_ZERO.
   static constexpr double kShoulderMiddleAngle = M_PI / 4.0;