AUI 1366 - Tree

Hey Marc,

After looking off Pei-Jung's work and talking with Michael, it looks like implementing NodeFocusManager for the aui-tree is going to result in heavier coding than just sticking with HandleKeypressEvent. Michael suggested just keeping what we have so far and sending it along to you. Per our conversation, I'm sending this back your way.

Let me know if I sent this one right : ) 

Thanks!