Server side support of MSV1_0_ALLOW_MSVCHAPV2 flag

[Sergey Urushkin]

Hello!
As I see, samba 4.5 doesn't respect MSV1_0_ALLOW_MSVCHAPV2 flag when 
acting as a server. This flag allows using mschapv2 with radius (VPN and 
802.1x) and is more secure than just "ntlm auth = yes" at the same time.
I think many administrators would be glad to have an ability to set 
"ntlm auth = mschapv2".

Client support has been already added here:
https://git.samba.org/?p=samba.git;a=commit;h=0b500d413c5b76188c0c566318be7079b777237c

Thanks for attention.

-- 
Best regards,
Sergey Urushkin