title: File IO inside CasperJS
body: <p>Is it possible do read/write files inside a CasperJS Script ?</p>
  
  <pre><code>var fs = require('fs');
  var data = fs.readFileSync('testdata.data', 'utf-8');
  console.log(data);
  </code></pre>
  
  <p>Calling <code>casperjs fileio.js</code>returns:</p>
  
  <pre><code>'undefined' is not a function
  </code></pre>
  
  <p>Even after running <code>npm install fs</code>.</p>
  
  <p>Bonus point if not : explain why ?</p>