added support for adding content to the bottom of a page

.themes/classic/source/_includes/after_footer.html

@@ -0,0 +1,5 @@
+{% include disqus.html %}
+{% include google_plus_one.html %}
+{% include twitter_sharing.html %}
+{% include google_analytics.html %}
+{% include custom/after_footer.html %}

.themes/classic/source/_includes/custom/after_footer.html

@@ -0,0 +1,3 @@
+{% comment %}
+  Add content to be output at the bottom of each page. (You might use this for analytics scripts, for example)
+{% endcomment %}

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

@@ -9,9 +9,6 @@
     </div>
   </div>
   <footer role="contentinfo">{% include footer.html %}</footer>
-  {% include disqus.html %}
-  {% include google_analytics.html %}
-  {% include google_plus_one.html %}
-  {% include twitter_sharing.html %}
+  {% include after_footer.html %}
 </body>
 </html>