title: How can I add bootstrap's icon to button_to in rails3
body: <p>My original code is</p>
  
  <pre><code>&lt;%= button_to 'Destroy', girl, confirm: 'Are you sure?', :disable_with =&gt; 'deleting...', method: :delete, :class =&gt; 'btn-mini btn-danger btn'  %&gt;
  </code></pre>
  
  <p>I'd like to add an icon in front of the word "Destroy".</p>
  
  <p>icon tag is this</p>
  
  <pre><code>&lt;i class="icon-pencil icon-white"&gt;&lt;/i&gt;
  </code></pre>
  
  <p>How can I do that??</p>