title: XmlUtil.serialize : Outputs tags in uppercase
body: <p>I am trying to create a valid html document from html</p>
  
  <pre><code>    String content = getContent()
      def parser = new org.cyberneko.html.parsers.SAXParser()
      parser.setFeature('http://xml.org/sax/features/namespaces', false)
      def slurper = new XmlSlurper(parser)
      def html = slurper.parseText(content)
      String xml = XmlUtil.serialize(html, )
      println xml
  </code></pre>
  
  <p>However, the output will have all the tag names in uppercase eg. HTML/BODY
  How do I stop it from capitalizing the tags.</p>