[strongSwan] xauth_radius plugin with Challenge/Response support

[Martin Willi]

Hi Gerald,

> The main reason I created the xauth_radius plugin, was to have
> Challenge/Response to support OTP (it works at least with Cisco clients
> like on the iPhone), so hopefully it will make it after 5.1.0 into
> strongswan.

Yes I'll take a look at that. Unfortunately I couldn't manage to get
FreeRADIUS to send challenges for Google-Authenticator codes yet...

Regards
Martin