title: React img tag issue with url and class
body: <p>I have the following simple react code in my JSX file:</p>
  
  <pre><code>/** @jsx React.DOM */
  
  var Hello = React.createClass({
      render: function() {
          return &lt;div&gt;&lt;img src='http://placehold.it/400x20&amp;text=slide1' alt={event.title} class="img-responsive"/&gt;&lt;span&gt;Hello {this.props.name}&lt;/span&gt;&lt;/div&gt;;
      }
  });
  
  React.renderComponent(&lt;Hello name="World" /&gt;, document.body);
  </code></pre>
  
  <p>The output in the DOM is as follows:</p>
  
  <pre><code>&lt;div data-reactid=".0"&gt;
    &lt;img src="http://placehold.it/400x20undefined1" data-reactid=".0.0"&gt;
    &lt;span data-reactid=".0.1"&gt;
      &lt;span data-reactid=".0.1.0"&gt;Hello &lt;/span&gt;
      &lt;span data-reactid=".0.1.1"&gt;World&lt;/span&gt;
    &lt;/span&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I have two issues with it:</p>
  
  <ul>
  <li>The image URL is rendered incorrectly, it is rendered as '<a href="http://placehold.it/400x20undefined1">http://placehold.it/400x20undefined1</a>'</li>
  <li>The class on my image disappears</li>
  </ul>
  
  <p>Any ideas?</p>