Support reboot in non-chroot modes using grub and an init script

We use grub-2.06 as 2.12 has some packaging issues, and can't be
built in live-bootstrap for now.

steps/jump/move_disk.sh

@@ -32,6 +32,7 @@ if [ $((0x$(stat -c "%T" "/dev/${DISK}") % 8)) -eq 0 ]; then
     echo "Creating ext4 partition..."
     mkfs.ext4 -F -F "/dev/${DISK}1"
     DISK="${DISK}1"
+    echo DISK="${DISK}" >> /steps/bootstrap.cfg
 fi
 
 # Mount the partition, move everything into /external