This version adds support for dispute and recipient API as well as change the way requests are made to the server. Internally, the library now uses `application/json` as POST request body instead of `x-www-form-urlencoded`. The change should result a more consistent requests (as objects now serialized and sent as it is, instead of doing extra data transformation.)
- [Added] Add Dispute API support.
- [Added] Add Recipient API support.
- [Changed] Use JSON for POST body instead of URL-encoded form.