Fix for hiding of payment gateway rows on checkout table described in #597 and multiple AJAX requests

* Change js selectors not to hide table rows that have payment information
* Combined js selectors to perform single action when hiding, rather than hide then show
* Fix malformed class attribute on "Shipping Address" header row

See the discussion in #597 


Update:
* Added Fix multiple change events firing on single action. Seems that the .on/.off calls where out of balance, as each change occurred additional .change events were being added.