Bug 3674: reimplementation

05eb43f5fc00889420e03845b5059d80bf1663ad reverted a previous
implementation of 3674.

3674 was encoding the password field when it was meant to be disabled
(password='!'), and then, in Auth.pm we were trying to compare an
encoded '!' with '!', which will never succeed.

This gets sure we encode only provided passwords and also includes an
auto generated login.

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Signed-off-by: Ian Walls <ian.walls@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>