API: Decorators tests

[deandrebaker]

We need to add tests for the following:

• model_view_set_swagger_decorator returns a function that will apply the swagger auto schema decorator with the list of tags specified by the tags parameter for the list, create, retrieve, update, partial_update, and destroy methods on a class.
• api_view_swagger_decorator returns a function that will apply the swagger auto schema decorator with the list of tags specified by the tags parameter for the get and post methods on a class.