Use readAsArrayBuffer() instead of deprecated readAsBinaryString().

readAsBinaryString is now deprecated as per the 12 July 2012 Working Draft from the W3C
https://developer.mozilla.org/en-US/docs/Web/API/FileReader.readAsBinaryString

The prior version was working in latest versions of Chrome and FF,  but not IE11.  This fixes the problem in IE11.

Note, I ran the grunt build step and it worked nicely.  The dist folder is committed as well.