SLE 11 does not ship systemd and then using systemctl poweroff does not
work. Therefore we fall back to using /sbin/shutdown for machines without
systemd.
This fixes https://github.com/hashicorp/vagrant/issues/12487
We have started seeing occasional shutdown failures on openSUSE Tumbleweed with
Virtualbox inside a qemu virtual machine, where `shutdown -h now` would return
nil. While the machine is successfully turned off, the command fails and vagrant
reports an error.
This commit changes the shutdown command to launch in the background which
also triggers a shutdown, but always succeeds.
In order to get a SUSE guest running and installing fine i have added a
correct capability for installing rsync and nfs-client.
I have included SUSE naming fixes as well because SUSe doesnt get
spelled SuSE anymore :).
