Scroll to bottom of header instead of top of payment container (in case there are any alert messages)
Add refresh warning on checkout_payments page
Add client_timestamp to check against duplicate form submissions before the server returns any response
Track payments that fail from the CT API
Change payment confirmation page to allow refreshing
Merge pull request #157 from Crowdtilt/payment_flow_improvements

Fix payment form resubmission before server response and other payments flow improvements