[ssh_x509] other key formats from RFC 6187

[ssh_x509 at roumenpetrov.info]

Hi Roumen,

Is it correct that PKIX-SSH only implements the x509v3-ecdsa-sha2-* 
algorithms from RFC 6187?

That is, it does not support x509v3-ssh-dss, x509v3-ssh-rsa, or 
x509v3-rsa2048-sha256 - is that right?

Thanks,
Kent