Feature #81: Improve CD boot and shutdown
USB version does not ask to remove the media anymore
Since the console is now hidden by the shutdown splash, there is no message that tells to remove the USB media at shutdown. Indeed we should have 3 shutdown modes:
- CD -> remove the CD then press enter
- USB -> remove the USB media
- HD install -> nothing to do
We should then modify both the script which is writing the shutdown messages in the splash and the shutdown script which should detect whether we are running from CD, USB or internal HD.