Add a new flag, -systemdfds, which causes Red October to expect to be
provisioned on launch with file descriptors for sockets opened by
systemd. This is useful for socket activation, but also allows systemd
to bind privileged ports for us. I've included example systemd
configuration files that successfully start Red October as a service
user without admin rights but bound to 443 in a Jessie VM for me. They
need to be installed where systemd expects them, which on Jessie is
/etc/systemd/system/redoctober.service and
/etc/systemd/system/sockets.target.wants/redoctober.socket.
