[Samba] Ntlm_auth possible feature request.

[Plant, Dean]

We are looking to use ntlm_auth with the --require-membership-of= option
to restrict user access to the squid proxy.

Although this is a works great, because nearly all our users are given
Internet access, there is extra overhead of adding every user to the
"Allow Internet Group". It would make sense (to me anyway) to have the
inverse of this option, so as default everyone is granted access except
for a --not-member-of="Deny Internet Group". This allows simpler
administration of the user access group, assuming you have less users
being denied Internet access.

Thanks

Dean.