Adding universal-analytics package for tracking to google via the Measurement Protocol.
Tracking requests of the towtruck.js. This is pretty naive right now, but is also purely anonymous.
Using the env var in our layout for our google analytics account id.
Adding tracking code to the towtruck controller so that every time /towtruck.js is requested, we record the referrer.
Adding HOST to the sample .env file.
Merge branch 'master' of github.com:mozilla/towtruck into develop