AUI-1589 - extend aui-aria plugin with TableSortable class

Hi Jon,

Attached is another update for https://issues.liferay.com/browse/AUI-1589.

I made the changes according to Maira's comments on https://github.com/mairatma/alloy-ui/pull/109.  I also added some changes to the tests file that I must have forgot to add into that first pull I sent you.

Please let me know if there are any issues.

Thanks!