Inspired by Chris Whong’s Day in the Life of a NYC Taxi (http://nyctaxi.herokuapp.com/) and zev@zevross.com's Great Coffee to Great Beer (http://zevross.com/blog/2014/09/30/use-the-amazing-d3-library-to-animate-a-path-on-a-leaflet-map/).
Modified http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js to a secure url
Modified http://d3js.org/d3.v3.min.js to a secure url
https://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js
https://d3js.org/d3.v3.min.js