Add API to deal with the current payment.
Reconfigure DocData payment method configs.
Add a route for Payment to replace CurrentPaymentMethodInfo.

PaymentMethodInfoCurrent has been removed as this has been re-worked because it
wasn't working.
Rename DocData settings variable to COWRY_DOCDATA_*
PEP8
Remove PaymentMethodInfoList API and CurrentPaymentMethodInfoRoute.
Merge pull request #246 from benkonrath/i-wanna-pay

I wanna pay
Refresh voucher form after one is added

resolves #bb-230
Merge pull request #249 from gannetson/fresh-voucher-form

Fresh voucher form