Add THANK YOU! to DocData order description.

BB-697 #close
Ensure you can only add a donation to a project in campaign phase.
Only allow Order / Donations to be modified when Order is not closed.
Add response code checkwhen setting payment_method.
Add test for payment flow with payment cancel.
Deal with payment cancel exceptions.
Merge pull request #461 from benkonrath/order-payment-fixes

Order payment fixes