Remove 'disabled' from inputs in payments

With the Aug 27 commit, a601035bd199a49f7f74ccf04ed0d889ca895f3e, the inputs under `.payment-method` are being disabled on line 15 but never correctly undisabled. This fixes that issue. Looks like it is affecting most branches.
fixes #5467
fix handling of credit cards expiring in current month
fixes #5468