[jnc_io_ssh] fix: authenticate didn't clear private key if null was passed (hence, it was not possible to switch FROM private-key-auth to password-auth)
[jnc_io_ssh] fix: authenticate didn't clear private key if null was passed (hence, it was not possible to switch FROM private-key-auth to password-auth)

vovkos/jancy,vovkos/jancy,vovkos/jancy,vovkos/jancy,vovkos/jancy