whitespace
don't return attrlist, as it is useless
Add unbind function
Fix logging introducing a get_logger function

Code stolen from django-auth-ldap
Model: wrap up common bits to _get_connection().
Model: support calling build_*dn() with custom values.

This allows us to build DNs on uninstantiated classes.
Add bind_as() to support binding to different credentials.
Support bind_as() on a class.