Bug#504381: rootskel: noshell boot option for unattended installations

[Frans Pop <elendil@planet.nl>]

On Monday 03 November 2008, Colin Watson wrote:
>   * init: Add support for disabling the shells on tty2 and tty3 by
>     specifying a 'noshell' option on the kernel cmdline. Useful for
>     unattended installations in a public place.

We'll also need a patch for di-utils' user-params script to avoid the 
parameter being added to the command line for the installed system. And 
I'd also appreciate a patch to document it in the installation guide.

Both can just be added to this BR.

Cheers,
FJP