title: sitemesh 3 exclude root path
body: <p>when i visit localhost:8080 ， i want to get index.html that is not decorated.
  when i visit localhost:8080/admin, i want all the pages to be decorated.</p>
  
  <p>my config is </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;sitemesh&gt;
    &lt;!--   &lt;mapping path="/" exclude="true"/&gt; not work --&gt;
  &lt;mapping path="/index.html" exclude="true"/&gt;
  &lt;mapping path="/assets/*" exclude="true"/&gt;  
  &lt;mapping path="/admin*" decorator="/WEB-INF/decorators/decorator.html"/&gt;
  &lt;/sitemesh&gt;
  </code></pre>
  
  <p>index.html isn't decorated unless i visit localhost:8080:index.html</p>