Move gh-pages branch files into /docs and add test files

- Jekyll ignore `/docs` and `/test` folders when using from root
- Update Staticman config to point to correct branch and data file location
- Replace `{{ base_path }}` references with `absolute_url` filter
- Update documentation

docs/_includes/analytics-providers/google.html

@@ -0,0 +1,11 @@
+<script type="text/javascript">
+  var _gaq = _gaq || [];
+  _gaq.push(['_setAccount', '{{ site.analytics.google.tracking_id }}']);
+  _gaq.push(['_trackPageview']);
+
+  (function() {
+    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
+    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
+    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
+  })();
+</script>