Updated date picker spin button example

I have updated the date picker spin button example:
https://raw.githack.com/w3c/aria-practices/issue125-spinbutton-datepicker-example/examples/spinbutton/datepicker-spinbuttons.html

Changes:

  1.  Example has been moved to the issue125-spinbutton-datepicker-branch
  2.  Added ARIA hidden to redundant and inoperative visible components
  3.  Added regression tests

Jon Gunderson, Ph.D., CPWA
Coordinator of Accessible IT Group
University of Illinois at Urbana/Champaign
1207 S. Oak Street
Champaign, IL 61820

www: https://go.illinois.edu/jongund