Modify shooter control loop to take velocity.

- NOTE: Things compile and run, but the output never actually stabilizes.
Before this can be used, new motor_plant constants for the shooter MUST
be determined.
diff --git a/bot3/control_loops/shooter/shooter.h b/bot3/control_loops/shooter/shooter.h
index 63c194f..efc1f1b 100644
--- a/bot3/control_loops/shooter/shooter.h
+++ b/bot3/control_loops/shooter/shooter.h
@@ -33,18 +33,10 @@
 
  private:
   // The state feedback control loop to talk to.
-  ::std::unique_ptr<StateFeedbackLoop<2, 1, 1>> loop_;
+  ::std::unique_ptr<StateFeedbackLoop<1, 1, 1>> loop_;
 
-  // History array and stuff for determining average velocity and whether
-  // we are ready to shoot.
-  static const int kHistoryLength = 5;
-  double history_[kHistoryLength];
-  ptrdiff_t history_position_;
   double average_velocity_;
 
-  double position_goal_;
-  double last_position_;
-
   // For making sure it keeps spinning if we're shooting.
   double last_velocity_goal_;