Credit goes to Peter Cook for giving permission to use code from his Circular Heat Chart in D3.EZ.
Uses D3.EZ Reusable Chart Library
forked from jamesleesaunders's block: D3.EZ : Reusable Circular Heat Chart
Modified http://rawgit.com/jamesleesaunders/d3.ez/master/d3.ez.js to a secure url
https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js
https://rawgit.com/jamesleesaunders/d3.ez/master/d3.ez.js