move code for Twitter, Google +1 and Google Analytics to bottom of page, as inline <script> tags are always blocking page load

.themes/classic/source/_layouts/default.html

@@ -9,5 +9,8 @@
     </div>
   </div>
   <footer>{% include footer.html %}</footer>
+  {% include google_analytics.html %}
+  {% include google_plus_one.html %}
+  {% include twitter_sharing.html %}
 </body>
 </html>