set default background and reboot/shutdown commands

Index: regreet.sample.toml
--- regreet.sample.toml.orig
+++ regreet.sample.toml
@@ -4,7 +4,7 @@
 
 [background]
 # Path to the background image
-path = "/usr/share/backgrounds/greeter.jpg"
+path = "/etc/X11/xenodm/pixmaps/OpenBSD_15bpp.xpm"
 
 # How the background image covers the screen if the aspect ratio doesn't match
 # Available values: "Fill", "Contain", "Cover", "ScaleDown"
@@ -34,10 +34,10 @@ theme_name = "Adwaita"
 
 [commands]
 # The command used to reboot the system
-reboot = ["systemctl", "reboot"]
+reboot = ["/sbin/shutdown", "-r", "now"]
 
 # The command used to shut down the system
-poweroff = ["systemctl", "poweroff"]
+poweroff = ["/sbin/shutdown", "-p", "now"]
 
 # The command prefix for X11 sessions to start the X server
 x11_prefix = [ "startx", "/usr/bin/env" ]
