Move over to using the Universal Analytics snippet

Deprecate the old classic GA snippet in favor of using the universal
snippet. The new universal snippet also contains commented out
features such as display features and enhanced link attribution.

The snippet has been tested against a website that pulled in 400
million page views over the course of a month, it also had custom
event tracking implemented.

Snippet provided courtesy of @rmarescu, which originated here:
https://github.com/reed/turbolinks-compatibility/issues/41