AUI-1044 - In aui-tree-node Add option to prevent selecting all child nodes in radio and task.

Hey @pat270,

Attached is an update for http://issues.liferay.com/browse/AUI-1044.  Can you add a test for this change in AUI?  We also need to add a HISTORY.md entry for why this change was made.

Please let me know if you have any questions.  Thanks!