Update presets-loader.js (jishi#563)

Enables running on node 4.xx
Strict mode needs to be declared

Author: rafale77

lib/presets-loader.js

@@ -1,3 +1,4 @@
+"use strict";
 const fs = require('fs');
 const util = require('util');
 const path = require('path');
@@ -84,4 +85,4 @@ try {
   logger.warn(e.message);
 }
 
-module.exports = presets;
+module.exports = presets;