This will probably be very noisy in the GA reports. Every open will be recorded under "Active Pages" as "wiki edit document".

The [sitepoint article](http://www.sitepoint.com/using-beacon-image-github-website-email-analytics/) says "the path can be the email subject, the title of the newsletter campaign, or whatever else you see fit." So we might want to do `tracking_counter_name = subject` so the opens are listed as, e.g.:

* [MDN] Page "Add-ons" changed by wbamberg
* [MDN] Page "Modifying Web Pages Based on URL" changed by wbamberg