Added ping command functionality.

U2F_CMD.cpp

@@ -2,6 +2,7 @@
 #include "u2f.hpp"
 #include "U2F_Msg_CMD.hpp"
 #include "U2F_Init_CMD.hpp"
+#include "U2F_Ping_CMD.hpp"
 
 using namespace std;
 
@@ -11,6 +12,8 @@ shared_ptr<U2F_CMD> U2F_CMD::get(const shared_ptr<U2FMessage> uMsg)
 	{
 		switch (uMsg->cmd)
 		{
+			case U2FHID_PING:
+				return make_shared<U2F_Ping_CMD>(uMsg);
 			case U2FHID_MSG:
 					return U2F_Msg_CMD::generate(uMsg);
 			case U2FHID_INIT: