wsgi: Gunicorn => Chaussette

plaintext: 21k req/sec => 114k req/sec
wsgi: reduce processes.
flask: json: 5k => 7k req/sec
Add circus to requirements.
Add missing file.
flask: Update benchmark_config
flask-py3: Remove gunicorn.
flask-pypy: Remove gunicorn.
Add missing file.
mv
895 all changes work

Works straight out the box, had to install circus manually,
however in future installations that will be taken
care of by the install script.
Merge branch '895'