Update README
#1: Fix Android bug with filter buttons

Android browsers prior to v3.0 do not support <a
href="http://mdn.beonex.com/en/DOM/element.classList.html"
target="_blank">`element.classList`</a>. jQuery can usually handle this
but jQuery class helpers don't work on SVG objects. Fixed with <a
href="https://github.com/eligrey/classList.js"
target="_blank">eligrey/classList.js</a> shim.
Make print charts responsive

Not sure this is 100% working