Update analytics code

[nukeador]

Piwik is now in a subdomain, code needs update

<!-- Piwik -->
<script type="text/javascript">
  var _paq = _paq || [];
  _paq.push(["setDomains", ["*.eventos.mozilla-hispano.org"]]);
  _paq.push(['trackPageView']);
  _paq.push(['enableLinkTracking']);
  (function() {
    var u=(("https:" == document.location.protocol) ? "https" : "http") + "://stats.mozilla-hispano.org/";
    _paq.push(['setTrackerUrl', u+'piwik.php']);
    _paq.push(['setSiteId', 2]);
    var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript';
    g.defer=true; g.async=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
  })();
</script>
<noscript><p><img src="https://stats.mozilla-hispano.org/piwik.php?idsite=2" style="border:0;" alt="" /></p></noscript>
<!-- End Piwik Code -->