Update package.json

Author: flovilmart

package.json

@@ -36,5 +36,8 @@
     "node-gcm": "^0.14.0",
     "npmlog": "^2.0.3",
     "parse": "^1.8.1"
+  },
+    "engines": {
+    "node": ">= 4.6.0"
   }
 }