1- GNOME 3.18 in void does not support reboot/shutdown currently without systemd.
Void does not use systemd, and we are relying on ConsoleKit2... the gdm/gnome-shell code needs
to be ported to support ConsoleKit2.

2- This error is shown when the avahi daemon is not running, install "avahi" and then start
its runit service to make this work correctly.