Ajaxify the checkout, closes #755
Prevent duplication of error messages
Fix for switching between ajaxified payment gateways
Allow the checkout to run without ajax
Replace ajax checkout using .live()
Fix purchase session wasn't being set with ajax
Fix ajax for when using ajaxified payment gateways
Swap the jquery selector in ajax checkout
AJAX checkout only when enabled
Use a different selector again, ajax checkout
Merge pull request #756 from Geczy/ajax-checkout

Ajaxify the checkout, closes #755