[REQUEST] Add Systemd service counter and failed services

[JoshuaPettus]

Such an awesome program, excellent job. Easily my new favorite system monitor. There is just one thing left and I can put htop to bed.

Could you add a counter for number of systemd services with the number that have failed? That would put it on par with htop in this area.

If you can improve on htop - would be a way to view the services and see their status.

Thank you!