Ticket #335. Upgraded seash to check for the validity of the public/private key pair before allowing authentication as that user. Also added a check to make sure that both public and private keys were provided.
Ticket #335. Upgraded seash to check for the validity of the public/private key pair before allowing authentication as that user. Also added a check to make sure that both public and private keys were provided.

sburnett/seattle,sburnett/seattle,sburnett/seattle,sburnett/seattle,sburnett/seattle,sburnett/seattle