Update REST API schema to use open standards

The release of Django REST Framework 3.5.x introduced support for multiple open API standards including OpenAPI/Swagger and CoreAPI.

See: http://www.django-rest-framework.org/api-guide/schemas/

Swagger, especially, facilitates the ability to do client code generation. This can lay the groundwork for simplifying the ability to create NSoT clients in other languages. At the very least, the new schema definitions are more robust and will provide a means for better programmatic enumeration of API endpoints for clients.