Don't clobber the upstream SWAGGER_SETTINGS

[waxlamp]

We are clobbering the upstream default value of SWAGGER_SETTINGS here.

As a side effect, this causes the Swagger page to show a Basic Auth login button, as well as the Django login button. We don't use basic auth for this project, but the Django login button is useful. That means, for now, there's no need to fix this. @brianhelba is working on a possible upstream fix to show just the Django login button. If and when he succeeds, this issue should be addressed.