Ditch veewee for packer

Veewee is behind vagrant's development and does not seem to function "out-of-the-box" anymore.

I tested Mitchell Hachimoto's new `packer` tool - there is even a converter, which I've tried http://www.packer.io/docs/templates/veewee-to-packer.html

It seem to be working. Migrate our definitions to packer is recommended

Still, there are issues with `preseed.cnf` or kickstarter. The definition might be buggy for debian wheezy