Simple Slider example for the ARIA Authoring practices guide

I have created a simple slider example for the ARIA Authoring practices for the APG group to  review:
http://jongund.github.io/aria-examples/slider-1.html

The code on my local github repository (jongund):
https://github.com/jongund/aria/tree/master/practices/examples/slider

The code should be part of the w3c/aria github.com repository:
https://github.com/w3c/aria/tree/master/practices/examples/

I made a pull request.
Jon