kwargs for username and password are being forgotten in mongoengine.connect

[edman]

Database connection without the "mongodb://" URI is not working for me. Username and password (among others) keyword arguments passed to mongoengine.connect are being popped from the conn_settings dictionary by the conditional statement at https://github.com/hmarr/mongoengine/blob/master/mongoengine/connection.py#L98.

The call mongoengine.connect('dbname', username='user', password='passwd', host='localhost', port=27017) reproduces the aforementioned behavior.