Update /etc/default/grub with GRUB_DEFAULT=saved

[ScottG489]

In order to specify what grub entry you want to reboot into this needs to be changed from GRUB_DEFAULT=0 to GRUB_DEFAULT=saved.

After that is done sudo update-grub also needs to be run so the changes apply to /boot/grub/grub.cfg.

This will allow us to run grub-reboot <entry #, title, etc> to set the default entry that will be used on next reboot, such as windows.

[ScottG489]

The auto installer seems to make the label for the drive be ubuntu-autoinstall-<date>. Is there a way to specify the label with the tool? We'll be creating a grub entry that will be looking for a specific label. We should be able to change the label with another tool otherwise if the tool doesn't support this.