Support multiple transaction types

[toppa]

As a merchant, I want to choose the Cybersource transaction type, so that I can use the type that is most appropriate for my business.

The types are:

• Standard Transaction Endpoints
  • authorization
  • authorization,create_payment_token
  • sale
  • sale,create_payment_token
• Create Standalone Payment Token Endpoints
  • create_payment_token
• Update Payment Token Endpoints
  • update_payment_token
• iFrame Standard Transaction Endpoints (same as above)
• iFrame Create Standalone Payment Token Endpoints (same as above)
• iFrame Update Payment Token Endpoints (same as above)

TBD: what to do with the payment token, for supporting recurring payments

[toppa]

This is done. I made it so the payment endpoint and transaction type can be associated with the profile. I made the handling of signed fields more flexible, so that any fields that are not listed as unsigned fields will be automatically handled as signed fields, as there can be a lot of different use cases.