Response struct should allow multiple tokens

[oyeb]

Motivation

To complete a single transaction (say, authorization) with some gateways, various tokens need to be created like customer_token, card_token, session_token, etc. Some tokens expire, some don't and we should return these tokens to the caller for possible re-use.

Proposed Solution

Rename the token field to tokens of the type: keyword.

If the following tokens are generated during an authorization: customer_token, card_token, then they can be returned like so:

%Response{
  ...
  tokens: [customer: "customer_token", card: "card-token"]
}

Todo

• [ ] Make the requested change in response.ex
• [ ] Update docs in response.ex
• [ ] Fix tests that break due to this change.
• [ ] Review affect of this new functionality for:
  • [ ] CAMS
  • [ ] Monei
  • [ ] Trexle
  • [ ] AuthorizeNet
  • [ ] Paymill
  • [ ] GlobalCollect

[barthr]

Should the value of tokens be a keyword list? I suppose those keys are unique. I think maybe a map would be more sufficient. Anyway, I could tackle this issue if no one else is working on it!