Populates our User object with information from the LDAP directory.

def _populate_user(self):
        """
        Populates our User object with information from the LDAP directory.
        """
        self._populate_user_from_attributes()
        self._populate_user_from_group_memberships()
        self._populate_user_from_dn_regex()
        self._populate_user_from_dn_regex_negation()