Consolidate user create/delete paths in smbpasswd

Consolidate user create/delete paths in smbpasswd

This patch changes the way smbpasswd behaves when adding/deleting users.
smbpasswd now calls pdb_create_user/pdb_delete_user, this means that if
add/delete user scripts are configured then they are used to create or
delete unix users as well. If the scripts are not defined the behavioris
unchanged.
This also allow to use smbpasswd -a/-x with ldapsam:editposix to allow
automatic creation/deletion of users.

Signed-off-by: Günther Deschner <gd@samba.org>