AUI-1353 - Make aui-datepicker accessible

Hi @Robert-Frampton,

Attached is an update for https://issues.liferay.com/browse/AUI-1353.

I made changes to the _onUseInputNode method so that it won't create multiple listeners for the same node.  I also removed the other listener that was being created in _focusPopover.  After some thought I realized it wasn't necessary as the user can tab into the table.

I also fixed a couple issues with the dependencies that I noticed.

Please let me know if there are any issues.

Thanks!