title: How to add class to an image_tag rails helper
body: <p>I have the following code:</p>
  
  <pre><code>&lt;%= image_tag iterator.image.url(:small), :class =&gt; "img_preview" %&gt;
  </code></pre>
  
  <p>But the rendered HTML shows:</p>
  
  <pre><code>&lt;img src="/actives/hotels/13/small/clean_wave.jpg?1317675452" alt="Clean_wave"&gt;
  </code></pre>
  
  <p>Why the "class" attribute isn't there?</p>
  
  <p>Thank you!</p>