Bug#266480: removal of gentleblue make machines unable to boot

[Stefanos Harhalakis]

  I'm using gentleblue splashimage on many of my machines since it is a very 
nice one. I've used it on some servers too. Those servers will not boot after 
the last upgrade because grub will determine that /boot/grub/splash.xpm.gz 
does not exist and it will wait for a keypress. Worst, the upgrade process 
will not even warn about this. Please add it back or fix it using the 
postinst script.

  BTW it was a very nice splashimage...