'Collapsible' is not working well when the widget inherits options from collapsibleset.

Hi all.

I find a bug in collapsible.
'Collapsible' is not working well when the widget inherits options from collapsibleset.

If you visit below URL, you should see the malfunction.
http://hyunsook.github.io/jqm-debug/latest/collapsibleset-inset_origin.html

The selector, :mobile-collapsibleset, can not find the collapsibleset within running _create().
Because this selector only can find the DOM after collapsibleset is created.

I think, we have two solutions.
First is to change widget creation order.
Second is to use a legacy selector (:jqmData(role='collapsibleset') ).
This PR contain second solution.

If you visit here, you would see the normal operation.
http://hyunsook.github.io/jqm-debug/latest/collapsibleset-inset_after.html

If there are any problems or mistakes on that PR, please let me know.
Thanks in advance.