[bug 850816] Add Optimizely script behind "optimizely" flag.

migrations/201-add-optimizely-flag.sql

@@ -0,0 +1,2 @@
+INSERT IGNORE INTO `waffle_flag` (`name`, `everyone`, `superusers`, `staff`, `authenticated`, `rollout`, `note`, `testing`, `created`, `modified`)
+    VALUES ('optimizely', 0, 0, 0, 0, 0, '', 0, NOW(), NOW());

templates/base.html

@@ -214,6 +214,12 @@
   {{ js(script) }}
 {% endfor %}
 
+{# Optimizely script for A/B testing - Bug 850816 #}
+{% if waffle.flag('optimizely') %}
+  <script src="//cdn.optimizely.com/js/25134714.js"></script>
+{% endif %}
+{# End Optimizely #}
+
 {% if request.LANGUAGE_CODE == 'en-US' %}
   {# tabzilla is en-US only for now #}
   <script src="//www.mozilla.org/tabzilla/media/js/tabzilla.js"></script>