protocol/nefarious: add Nefarious 2 SASL support
protocol/nefarious: send the account timestamp in svslogin
Merge pull request #248 from grawity/nefarious2-sasl

protocol/nefarious: add Nefarious 2 SASL support
Pass the entire myuser_t* to svslogin_sts()

Some protocol modules, like nefarious, want to access other fields than
just `->name`; this avoids having to call myuser_find() just to find the
same myuser that's already known. (Ref: #248)

It does, however, change the protocol module API.
Merge pull request #249 from grawity/svslogin-myuser_t

Pass the entire myuser_t* to svslogin_sts()
services: accept auth from other servers

For experiments with custom SASL auth agents. INSECURE.
saslserv/gssapi: add module

This requires libgsasl, and theoretically could support other mechanisms
as well.