WIP on PaymentRequestBodyBuilder
Adds builder for payment request body. Refactors tests. Adds some model interfaces
Refactors PaymentRequestBodyBuilder and PaymentService classes and tests
WIP on capture call
UNSTABLE. WIP on capture method for credit card payment
Adds capture and authorization model classes and builder
Refactoring of request send method, with introduction of a trait
Adds missing builders and their tests
Adds methods to store plain data for AccessToken, Authorization, Payment and Capture objects.
Nano refactoring of PaymentRequestBodyBuilder
Minor fixes
Adds error handling for paypal error response
Refactoring of request body building, now the PaymentRequestBodyBuilderTest::build returns json by default. Updates README
Adds validator for request body in create and authorize calls. Adds json schema validation for all the classes used in the implemented features
Adds strong type inting on PaypalData trait
Updates README
Updates README
Updates README