Copter: show firmware version on param fetch

fixes pull #1320

thanks Arthur!

ArduCopter/GCS_Mavlink.pde

@@ -897,6 +897,12 @@ void GCS_MAVLINK::handleMessage(mavlink_message_t* msg)
 
     case MAVLINK_MSG_ID_PARAM_REQUEST_LIST:         // MAV ID: 21
     {
+        // mark the firmware version in the tlog
+        send_text_P(SEVERITY_LOW, PSTR(FIRMWARE_STRING));
+
+#if defined(PX4_GIT_VERSION) && defined(NUTTX_GIT_VERSION)
+        send_text_P(SEVERITY_LOW, PSTR("PX4: " PX4_GIT_VERSION " NuttX: " NUTTX_GIT_VERSION));
+#endif
         handle_param_request_list(msg);
         break;
     }