Popup refactor

1. Move all style properties to widget.tss
2. Create close button dynamicaly to make widget more independence
3. Cleanup
`var children = args.children || [];` resolve this situation. Or did you mean that **child** can be *null* in some situation? It isn't problem also because TiViewProxy check it.
I know that map performance is less than loop. But how many items may be insert into popup? On the other hand code became cleaner.