Explicitly stop the PIDController Notifier in the destructor (#48)

This helps reduce the probability of a PID Controller Segmentation Fault.

wpilibc/athena/src/PIDController.cpp

@@ -78,6 +78,8 @@ void PIDController::Initialize(float Kp, float Ki, float Kd, float Kf,
 }
 
 PIDController::~PIDController() {
+  //forcefully stopping the notifier so the callback can successfully run. 
+  m_controlLoop->Stop();
   if (m_table != nullptr) m_table->RemoveTableListener(this);
 }