Installer: reactivate booting from installed hard disc
Installer: reactivate booting from installed hard disc

Currently we always boot from second hard disc even though Artemis
already can create grub files to boot from the hard disc that was
mounted as / in the first image precondition. With this patch we use
this feature again and boot from this partition.

tapper/Tapper-Installer,tapper/Tapper-Installer