title: respond_with json oddness
body: <pre><code> respond_to :json
  
    def create
      respond_with('test')
    end
  </code></pre>
  
  <p>I was just doing some testing and the above gives me an error of:</p>
  
  <p>undefined method `test_url' for #</p>
  
  <p>Why is it trying to turn test into a url? Is this a bug?</p>