MXS-1494: Add missing replication credentials parameters

The parameters weren't added to the list of module parameters.

server/modules/monitor/mysqlmon/mysql_mon.cc

@@ -542,6 +542,8 @@ MXS_MODULE* MXS_CREATE_MODULE()
                 MXS_MODULE_OPT_PATH_X_OK
             },
             {CN_SWITCHOVER_TIMEOUT, MXS_MODULE_PARAM_COUNT, DEFAULT_SWITCHOVER_TIMEOUT},
+            {CN_REPLICATION_USER, MXS_MODULE_PARAM_STRING},
+            {CN_REPLICATION_PASSWORD, MXS_MODULE_PARAM_STRING},
             {MXS_END_MODULE_PARAMS}
         }
     };