support https flask app code example

Example: flask on gevent over https

# file: gevent_app_https.py
from flask_app import app
from gevent.pywsgi import WSGIServer

http_server = WSGIServer(('0.0.0.0', 443), app, keyfile='privkey.pem', certfile='cacert.pem')
http_server.serve_forever()