Renamed folders for consistency, using sim/athena/shared schema (#27)

Rename the following folders:
hal/lib/Athena -> hal/lib/athena
hal/lib/Desktop -> hal/lib/sim
hal/lib/Shared -> hal/lib/shared
wpilibc/Athena -> wpilibc/athena
wpilibc/simulation -> wpilibc/sim

Windows users may need to run gradlew clean after updating.

wpilibc/sim/include/SampleRobot.h

@@ -0,0 +1,26 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2008-2016. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include "RobotBase.h"
+
+class SampleRobot : public RobotBase {
+ public:
+  SampleRobot();
+  virtual ~SampleRobot() = default;
+  virtual void RobotInit();
+  virtual void Disabled();
+  virtual void Autonomous();
+  virtual void OperatorControl();
+  virtual void Test();
+  virtual void RobotMain();
+  void StartCompetition();
+
+ private:
+  bool m_robotMainOverridden;
+};