Standardize category names and unify to have one category per class. Move files to "Additions" directory.

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.

Refactor partial address handling to prevent a partial address to be applied on a completed checkout

fixes for integration tests

fix partialAddress unit test

Allow for partial address flag to be set to false on update

Prevent partial address from being sent post Apple Pay authentication

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.

Make Playground.app rely on Dynamic framework

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