v0.13.0

Added

• [Braintree.Webhook] Allow passing options to webhook parser/validator, similar to other API functions.

• [Braintree.Plan] Expand plan functionality with delete, improved guard clauses, and better response code formatting.

• [Braintree.Customer] Support ACH Direct Debit payment methods.

Fixed

• [Braintree.HTTP] Fix error in response type specification.

  This typespec error wasn't caught given the current dialyzer settings, but could cause issues for clients expecting things like {:error, :not_found}.