Audit middleware does a lot of faking up environments and calling
methods instead of just running the middleware. It's a whole bunch
easier to just run the middleware wherever possible.
This means we don't have to stub context from tests as these tests
actually pass through the wsgi layer correctly. Ideally we would do more
of this.
Change-Id: I95377f030b07ffae18698ecc3c82cc6aa1dddbc7