title: CssRewriteUrlTransform with or without virtual directory
body: <p>We are using MVC Bundling in our site, <code>CssRewriteUrlTransform</code> makes sure that the image urls work from the dynamic bundle css file. </p>
  
  <p>But this only works when not using a virtual directory, i.e </p>
  
  <p><code>http://localhost/VirttualDir</code> does not work but <code>http://localhost/</code> does. This is because the <code>CssRewriteUrlTransform</code> tranform does not take the virtual folder into account when rewriting the url. So if a image real path is <code>localhost/vdir/content/img/foo.png</code> it will rewrite it to <code>localhost/content/img/foo.png</code> which is wrong </p>