This module provides authentication via ssh-agent.

It may take 5 arguments, file=/path/to/authorized_keys, debug,
allow_user_owned_authorized_keys_file,
authorized_keys_command=/path/to/command and
authorized_keys_user=username. If an ssh-agent listening at
SSH_AUTH_SOCK can successfully authenticate that it has the secret key
for a public key in the specified file, authentication is granted,
otherwise authentication fails.
