Remove UUIDs from URLs sent to Google Analytics

If all our URLs are unique (because they contain service/job/template
IDs) then it makes it hard to aggrate how users are behaving across a
range of services/jobs/templates.

This commit replaces anything that looks like a UUID in a URL with `…`.

app/templates/admin_template.html

@@ -135,6 +135,10 @@
       m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
     })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
     ga('create', 'UA-75215134-1', 'auto');
-    ga('send', 'pageview');
+    // strip UUIDs
+    page = window.location.href.replace(
+      /[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}/g, '…'
+    )
+    ga('send', 'pageview', page);
   </script>
 {% endblock %}