Add argument to override logging.file configuration

[rooty0]

This is very useful when run sshesame with init.d (system v init) or systemd or rc.d - whatever.

So the idea is to run executables something like sshesame -logging null to redirect output to stdout, so for example systemd could write logs to /var/log/blah.log with root owner while the app itself runs under nobody or any non-privileged user