Various: Use ES5, users should polyfill on their own for IE8 support

Fixes #259, #260 and #244
(fix) Various: Use ES5, users should polyfill on their own for IE8 support

Create a polyfilled tests version, because we need to cover IE8
(fix) Various: Use ES5, users should polyfill on their own for IE8 support

Update README
(fix) Various: Use ES5, users should polyfill on their own for IE8 support

Update README
(fix) Various: Use ES5, users should polyfill on their own for IE8 support

Update README
(fix) Various: Use ES5, users should polyfill on their own for IE8 support

Update README
(fix) Various: Use ES5, users should polyfill on their own for IE8 support

Update README