Ticket 47944 - Implement sd_notify for systemd
    
    Bug Description:  Systemd assumes processes are ready as soon as the PID file
    is ready.
    
    Fix Description:  By calling sd_notify, we are able to tell systemd when we are
    actually ready to process requests (or as close to it as possible), and when
    we are shutting down.
    
    https://fedorahosted.org/389/ticket/47977
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)