title: How to copy/include external file in webpack
body: <p>My project depends on react and mxGraph, and i am using webpack as bundle tool. Currently i am building react using webpack and manually including 
  <code>&lt;script type="text/javascript" src="js/mxGraph/mxClient.js"&gt;&lt;/script&gt;
  </code>
  in index.html file. Now i want to  concat/add mxClient.js file content to bundle.js file generated by webpack. </p>
  
  <p>index.js</p>
  
  <pre><code>var React = require('react'),
      ReactDOM = require('react-dom');
  
  window.React = React;
  window.ReactDOM = ReactDOM;
  </code></pre>
  
  <p>this generates bundle.js file with react deps to this i want to add/append mxClient.js content to bundle.js via webpack</p>