This commit should be eventually rebased and this msg edited

 - use sh -e instead set -e
 - use title instead email when configure re6stnet

  This script still on experimental stage, only works for debian 7.
  The preseed.cfg is a pure netinstall debian automation setup, it
  don't install slapos by itself for now.

In case of vpn, use it.

No need to run slapgrid, as it is run by cron every minute.
Also follows rule of least surprise.

But keep being verbose if it failed.

last command in script may fail, but it is not a problem.

Much easier to debug.

It's not a bug, it's a feature.

Sometimes we want a second disk even inside of VM.
Even weirder, maybe you want a vm inside of your vm (now possible with new KVM).

No need for endscript.