This adds a attributes to checkout. These objects are returned as an array of dictionaries, but expected as dictionaries when posting the checkout, so we're required to serialize the objects correctly. API now also returns the `note` on a checkout, so I have added a test for that.

Remove Playground scheme

Minor framework fix

Add status page to Advanced Sample App demo

Add NSNull checks and convert to nil

Make Playground.app rely on Dynamic framework

1.2.1 Release

Fix shipping rate issue for Apple Pay

Add note to BUYCheckout

BUYProductViewController: Support for bottom inset when presented with tab bar and/or toolbar

Remove team IDs

Framework updates, improved Carthage support

Removed static scheme, updated targets and schemes for improved carthage support. Updated readmes to reflect the changes.

Dynamic framework, Cocoapods fixes, Carthage support, readmes

Add tests for product tags

Generics / Nullability Annotations