Add some logging

Especially for things like LDAP connections errors where we want to show a simple error to the user but need the actual exception in the logfile so admins/developers can figure out what exactly went wrong.

See https://docs.python.org/2/howto/logging.html#library-config on how to properly setup logging in a library.

Start by reviewing the LDAP connection error paths and the Python logging library guidance linked in the issue. Identify where user-facing errors are produced and where diagnostic exceptions should be recorded. Done means administrators can find the underlying exception in the log while users still receive a simple error.

Written by the indexing model from the issue text.