Enforce 'client plaintext auth', 'client lanman auth' and 'client ntlmv2 auth'.

Enforce 'client plaintext auth', 'client lanman auth' and 'client ntlmv2 auth'.

(this now causes things like the LANMAN protocol and contacting servers with 'encrypt passwords = no' set to fail, if configured)

'client ntlmv2 auth' (a BOOL) forces both plaintext and lanman off, and is the
most secure setting for compatible hosts.

Perhaps we should change this to 'client minimum auth'?

Andrew Bartlett
(This used to be commit e1fb681e4c921456fde154b87687722a18ed4aac)