Changes to Creates an External Payment Method.

added the non-success response with the status 400

removed the non-success response with the status 404

removed the easypay enum value from the payment_method/type response property for the response status 200

removed the easypaycc enum value from the payment_method/type response property for the response status 200

removed the eupago enum value from the payment_method/type response property for the response status 200

removed the external_payment_gateway enum value from the payment_method/type response property for the response status 200

removed the hipay enum value from the payment_method/type response property for the response status 200

removed the ifthenpay enum value from the payment_method/type response property for the response status 200

removed the khipu enum value from the payment_method/type response property for the response status 200

removed the manual enum value from the payment_method/type response property for the response status 200

removed the mercado_pago enum value from the payment_method/type response property for the response status 200

removed the moneybookers enum value from the payment_method/type response property for the response status 200

removed the pagseguro enum value from the payment_method/type response property for the response status 200

removed the paypal enum value from the payment_method/type response property for the response status 200

removed the payu enum value from the payment_method/type response property for the response status 200

removed the servipag enum value from the payment_method/type response property for the response status 200

removed the stripe enum value from the payment_method/type response property for the response status 200

removed the webpay_cl enum value from the payment_method/type response property for the response status 200