[sr-dev] k/auth_radius module based on s/auth module

[Juha Heinanen]

i have now converted k/auth_radius module to use the famed
s/auth module.  all functionality of existing auth_radius is preserved
except for this:

       If an empty string "" is used (as realm parameter) then the
       server will generate it from the request. In case of REGISTER
       requests To header 
       field domain will be used (because this header field
       represents a user being registered), for all other messages
       From header field domain will be used.

so the user needs to always give the realm ($td/$fd/...).

regarding s/auth module, there are differences in parameters as compared
to k auth module and www_challenge()/proxy_challenge() have been
replaced by digest_challenge avp.  this will be shown in README example.

is it ok if i commit the changes or does anyone else care if i'm the
only radius user?

-- juha