title: Access file selected with paper-input
body: <p>I'm trying to upload a file chosen through a Polymer <code>&lt;paper-input type="file" id="filepicker"&gt;</code> element but when i try to access the file with:</p>
  
  <pre><code>var file = this.$.filepicker.files
  </code></pre>
  
  <p>i get a <code>files is not defined</code> error.</p>
  
  <p>I haven't found any other methods to access files in paper inputs so I'm not sure what the problem is here.</p>
  
  <p>Any help would be appreciated!</p>