android.moparisthebest.org/.themes/classic/source/_includes/google_plus_one.html

{% if site.google_plus_one %}
  <script type="text/javascript">
    (function() {
      var script = document.createElement('script'); script.type = 'text/javascript'; script.async = true;
      script.src = 'https://apis.google.com/js/plusone.js';
      var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(script, s);
    })();
  </script>
{% endif %}