Integrations::HeidelpayHCO module
simple HeidelpayHco::Helper, set credential parameters + tests
HeidelpayHcoHelper: add static fields
HeidelpayHcoHelper#get_redirect_url
HeidelpayHcoHelper: amount
HeidelpayHcoHelper: locale and more static fields
HeidelpayHcoHelper: transaction mode
HeidelpayHcoHelper: order-id + usage
HeidelpayHcoHelper: include customer data
HeidelpayHcoHelper: successful response
add a bit of documentation