fi::rsh-command: prefer ssh over rsh

and properly detect ssh in fi::remote-lisp-args for proper quoting.
Without this fix, fi:common-lisp using ssh to remote systems does not
work.

Change-Id: I707423ffc9bec9dcdb22e34fb919a00840d5236e
Fix typo in last commit

Change-Id: If6206719ef5ec57e86b0a3f961b51b47935426d6