Fix warning regarding missing InstallMedia format

Author: deftdawg

basic.sh

@@ -24,5 +24,5 @@ qemu-system-x86_64 \
  -device ich9-ahci,id=sata \
  -drive id=ESP,if=none,format=qcow2,file=ESP.qcow2 \
  -device ide-hd,bus=sata.2,drive=ESP \
- -drive id=InstallMedia,if=none,file=BaseSystem.img \
+ -drive id=InstallMedia,format=raw,if=none,file=BaseSystem.img \
  -device ide-hd,bus=sata.3,drive=InstallMedia \