Made the demo work

[asgervelling]

usage_dash_flask_login.py, the demo, did not work. This was the traceback:

Traceback (most recent call last):
  File "/home/a/dev/undecided/dash-flask-login/usage_dash_flask_login.py", line 103, in <module>
    server.run_server(debug=True)
AttributeError: 'Flask' object has no attribute 'run_server'

I simply changed the line in the traceback to app.run_server(debug=True), and now it runs.