Removed empty default constructors and destructors from Gazebo plugins (#63)

simulation/frc_gazebo_plugins/encoder/src/encoder.cpp

@@ -9,10 +9,6 @@
 
 GZ_REGISTER_MODEL_PLUGIN(Encoder)
 
-Encoder::Encoder() {}
-
-Encoder::~Encoder() {}
-
 void Encoder::Load(physics::ModelPtr model, sdf::ElementPtr sdf) {
   this->model = model;
 

simulation/frc_gazebo_plugins/encoder/src/encoder.h

@@ -45,9 +45,6 @@ using namespace gazebo;
  */
 class Encoder : public ModelPlugin {
  public:
-  Encoder();
-  ~Encoder();
-
   /// \brief Load the encoder and configures it according to the sdf.
   void Load(physics::ModelPtr model, sdf::ElementPtr sdf);