Update ga.js

Author: talbring

_includes/ga.js

@@ -3,4 +3,5 @@
 m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
 })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
 ga('create', '{{ site.google_analytics }}', 'auto');
+ga('set', 'anonymizeIp', true);
 ga('send', 'pageview');