Feature request: Support application factories

[ikreb7]

It would be nice if you could support application factories. Then would be this possible:

from flask_httpauth import HTTPBasicAuth

auth = HTTPBasicAuth()

def create_app():
    app = Flask(__name__)
    auth.init_app(app)

[miguelgrinberg]

This extension does not require any arguments, not even the app instance, so you can use it with app factory style applications just fine. There is no need to call init_app, not because there is no support for it, but because there is nothing to initialize.