Braintree

* Add `DisputeAccepted`, `DisputeDisputed`, and `DisputeExpired` webhook constants
* Add `three_d_secure_pass_thru` to `CreditCard.create`, `CreditCard.update`, `PaymentMethod.create`, `PaymentMethod.update`, `Customer.create`, and `Customer.update`.
* Add `Verification` validation errors for 3D Secure
* Add `payment_method_token` to `CreditCardVerificationSearch`
* Add `recurring_customer_consent` and `recurring_max_amount` to `authentication_insight_options` for `PaymentMethodNonce.create`
* Add `FileIsEmpty` error code
* Eliminates usage of mutable objects for function parameters. Resolves 113 Thank you maneeshd!

* Split development and deployments requirements files out
* Add `Authentication Insight` to payment method nonce create
* Add ThreeDSecure test payment method nonces
* Add test `AuthenticationId`s
* Add `three_d_secure_authentication_id` to `three_d_secure_info`
* Add `three_d_secure_authentication_id` support for transaction sale
* Breaking Changes
* Require Python 3.5+
* Remove deprecated Transparent Redirect
* Remove deprecated iDeal payment method
* Apple Pay register_domains returns an ApplePayOptions object
* Remove `unrecognized` status from Transaction, Subscription, and CreditCardVerification
* Remove `GrantedPaymentInstrumentUpdate` kind from Webhook
* Remove Coinbase references
* Add GatewayTimeoutError, RequestTimeoutError exceptions
* Rename DownForMaintenanceError exception to ServiceUnavailableError
* Transaction `line_items` only returns the line items for a transaction response object. Use TransactionLineItem `find_all` to search all line items on a transaction, given a transaction_id
* Upgrade API version to retrieve declined refund transactions
* Remove all deprecated parameters, errors, and methods

* Add `RefundAuthHardDeclined` and `RefundAuthSoftDeclined` to validation errors
* Fix issue where managing Apple Pay domains would fail in Python 3.8+
* Add level 2 processing options `purchase_order_number`, `tax_amount`, and `tax_exempt` to `Transaction.submit_for_settlement`
* Add level 3 processing options `discount_amount`, `shipping_amount`, `ships_from_postal_code`, `line_items` to `Transaction.submit_for_settlement`

* Add support for managing Apple Pay domains (thanks ethier 117)
* Fix error when running against Python 3.8 (thanks felixonmars 114)
* Add `ProcessorDoesNotSupportMotoForCardType` to validation errors
* Add Graphql ID to `CreditCardVerification`, `Customer`, `Dispute`, and `Transaction`

* Set correct version for PyPi

* Forward `processor_comments` to `forwarded_comments`
* Add Venmo 'TokenIssuance' gateway rejection reason
* Add `AmountNotSupportedByProcessor` to validation error