Update grid-register.js

If register fail, print the failure details friendly to we newbee.

lib/grid-register.js

@@ -109,6 +109,9 @@ async function isAlreadyRegistered (jsonObject) {
       throw new Error(`Request failed`);
     }
     let responseData = JSON.parse(response.body);
+    if (responseData.success !== true) {
+      logger.debug("[ERROR] " + responseData.msg);  // if register fail,print the debug msg
+    }
     return responseData.success;
   } catch (err) {
     logger.debug("Hub down or not responding: ${err.message}");