Toggle disabled class on form group

The toggles the disabled state for the Province / State label after a country is selected. See screenshot: http://cl.ly/image/3720033w1846/Image%202014-08-26%20at%2010.59.01%20AM.png

Note: using `closest(".disabled")` is probably not the best way to select this element. I'm using simple forms and bootstrap and the disabled class that needs to be toggled is on the `.form-group` div, otherwise we could select the for attribute of the label directly. Not sure what happens with formtastic.