[windows service] Copied the 3 lines from etwist/twctl into etwist/service in order to also clean the cache in Windows service mode. Could be factorised with etwist/server.run

<div id="ajaxroot">
  <div class="ajaxHtmlHead">
    <script src="http://foo.js" type="text/javascript"> </script>
  </div>
  <h1>Hello</h1>
</div>