Button icon span

Working branch right now up for functional review for button re-write demo at http://view.jqueryui.com/button-icon-span/demos/button/

Spec: http://wiki.jqueryui.com/w/page/71756381/Button
I had hoped to eliminate the blur completely in chrome, safari, ie disabling an input also blurs it. However in firefox the input maintains focus when it is disabled. 

ill add an `activeElement` check though