Code review comment for ~xnox/casper:try-fix-unmount-cdrom

I built this into an ISO (properly, unlike my last comment) and it helps on boot but casper-stop now runs after /cdrom is unmounted and so doesn't prompt to remove media when it should. xnox thinks this can be fixed by correcting dependencies but I wonder if we should instead fix this by having the code that mounts /cdrom record in /run whether casper-stop should prompt and then deleting 90% of casper-stop. Possibly do the first for SRU and then the second for new releases?