updated smbpasswd to take the password on the command-line.

updated smbpasswd to take the password on the command-line.
two sets of operation:

as root: specify username password.
as user: specify old password  new password

this will allow shell scripts (like adduser) to include smbpasswd.

lkcl
(This used to be commit 7e5f1681bd538c3a1b576cff1d86fa8167704525)