Add support for configuration file and 2FA like yubikey

6 changes most of them are clean up to support properly the configuration files.

We have configuration file like that:

Host *
   ssh = ssh
Host poseidon                                                                   
    ssh = ssh -p 22                                                             
                                                                                
host scl64r1_1                                                                  
    port = 2239                                                                 
    predict = never


Last change add 2FA with yubikey/duosecurity