Move google analytics script to footer to avoid clogging the pipes during slowstart

Author: Munter

docs/_includes/footer.html

@@ -4,6 +4,7 @@
       href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.
     <p><em>Last updated: {{ site.time | date: "%c" }}</em>
   </span>
+  <script src="js/ga.js"></script>
   <script src="//cdnjs.cloudflare.com/ajax/libs/anchor-js/3.2.2/anchor.min.js"></script>
   <script>
     anchors.options = {

docs/_includes/head.html

@@ -9,6 +9,5 @@
   <!--[if lt IE 9]>
     <script src="js/html5shiv.min.js"></script>
   <![endif]-->
-  <script src="js/ga.js"></script>
   <script src="js/avatars.js"></script>
 </head>