Improve logging.

lib/zigbee.js

@@ -92,7 +92,7 @@ class Zigbee {
         // Mount cieApp
         this.shepherd.mount(cieApp, (err, epId) => {
             if (!err) {
-                logger.debug(`Mounted the cieApp (epId {epId})`);
+                logger.debug(`Mounted the cieApp (epId ${epId})`);
             } else {
                 logger.error(`Failed to mount the cieApp`);
             }