Move Django Middleware to WSGI Middleware

[Miserlou]

It was pointed out during the Q & A that the Django Middleware could be replaced with a WSGI Middleware that would live in Zappa core. This has a number of obvious benefits, such as more shared code, less client-specific code, and less client-specific integration.

[codingjoe]

👍 eventually this will also allow you to hook any WSGI application on

[Miserlou]

Looking forward to your PR @codingjoe ! 😜

[Doerge]

I have written an initial WSGI middleware for flask-zappa.

It's not quite there yet, but I'm still working on it. If anyone want to give it a spin with Django it can be found here..

[Miserlou]

Excellent work! Werkezeug was a good choice, and I'm happy to see the middleware moving upstream.