Add rollers to superstructure

Rebased off master

Change-Id: I905a678aab45cc999526c5076bba86bc8c6597c0
diff --git a/y2017/control_loops/superstructure/superstructure.q b/y2017/control_loops/superstructure/superstructure.q
index 49f93e5..24e5360 100644
--- a/y2017/control_loops/superstructure/superstructure.q
+++ b/y2017/control_loops/superstructure/superstructure.q
@@ -23,6 +23,9 @@
 struct IndexerGoal {
   // Indexer angular velocity goals in radians/second.
   double angular_velocity;
+
+  // Roller voltage. Positive is sucking in.
+  double voltage_rollers;
 };
 
 struct TurretGoal {