Add webhook subscriptions to Django apps (Python3 version)

 REST Hooks are advanced versions of webhooks. Traditional webhooks are usually
 managed manually by the user, but REST Hooks are not. They encourage RESTful
 access to the hooks (or subscriptions) themselves. Add several hooks for any
 combination of event and URLs, then get notificatied in real-time by a bundled
 threaded callback mechanism.
 .
 By reusing Django's signals framework, this library can be integrated into any
 existing Django app.
 .
 Using built-in actions, no work is required to support any basic created,
 updated, and deleted actions across any Django model. It also allows for custom
 actions (IE: beyond CRUD) to be simply defined and triggered for any model, as
 well as truly custom events that let an application send arbitrary payloads.
 .
 By default, this library will just POST Django's JSON serialization of a model,
 but it provides a serialize_hook method to customize payloads.
 .
 This package contains the Python 3 version of the library.