Jessie desktops

just opening this for review, comments welcome

still 3 major issues left that I'm aware of:

* d-i asks non-preseeded question (rt#3049)
* udev names network interface eth1 (rt#3050)
* puppet-trigger doesn't work on jessie (rt#3052)
(there are also the problems you've brought up previously, of course, e.g. staff not giving it attention and it breaking, taking extra time to maintain, etc.)

So I'll just remove it, I suppose.