Extend adduser to create "locked" accounts. Adduser can now lock an

Extend adduser to create "locked" accounts. Adduser can now lock an
account at creation, create accounts with a "*" password (so you can
use alternate authentication schemes without fearing a "default" password
biting you later), and blank passwords.

Yes, adduser could create a blank password account, but this makes it
slightly more difficult to shoot yourself in the foot.

The /etc/adduser.conf entries are:

# use password-based authentication for new users
# defaultusepassword =  "yes" | "no"
defaultusepassword = "yes"

# enable account password at creation
# (the password will be prepended with a star if the account isn't enabled)
# defaultenableaccount = "yes" | "no"
defaultenableaccount = "yes"

# allow blank passwords
# defaultemptypassword = "yes" | "no"
defaultemptypassword = "no"

Requested by: alfred
Reviewed by: alfred