title: Ruby on rails 4 app does not work in iframe
body: <p>How can I embed my rails app into another website via iframe?</p>
  
  <p>It works nicely with RoR 3, but not with RoR 4:</p>
  
  <pre><code>&lt;iframe src="http://myrailsapp.com/" width="100%" height="50" id="rails_iframe"&gt;error!&lt;/iframe&gt;
  </code></pre>
  
  <p>I tried to use <code>verify_authenticity_token</code> and <code>protect_from_forgery</code> options in my controller... seems it's something else (but I'm not sure).</p>
  
  <p>upd. Example:
  <a href="http://jsfiddle.net/zP329/" rel="noreferrer">http://jsfiddle.net/zP329/</a></p>