Nice to see more open-source solutions in this area. I've used the popular Django Rest Framework [1] to implement and manage APIs. Would there be a compelling reason to use Kong for the management aspect?
Saving you time and money!
Some features: http://getkong.org/plugins/Django REST Framework (or any other framework) to build your business logic and API services.
Kong is useful to scale and manage acceess to the API for API consumers (as oppose to end users) as well as a plugin system that abstracts HTTP tooling away from your API application, so you can scale them independently.