Added a conditional command that chooses 1 of 2 commands (#435)

Tests and documentation for ConditionalCommand were also added. This is a fixed version of #9, so it doesn't support lambdas.

Closes #9

wpilibcIntegrationTests/include/command/MockConditionalCommand.h

@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2017. 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 <Commands/ConditionalCommand.h>
+
+#include "command/MockCommand.h"
+
+namespace frc {
+
+class MockConditionalCommand : public ConditionalCommand {
+ public:
+  MockConditionalCommand(MockCommand* onTrue, MockCommand* onFalse);
+  void SetCondition(bool condition);
+
+ protected:
+  bool Condition() override;
+
+ private:
+  bool m_condition = false;
+};
+
+}  // namespace frc