added Debian 7.0 Wheezy boxes, released on May 4th, 2013

Boxes were build from debain 7.0 netinstall iso with veewee tool

 * Debian Wheezy current stable release http://www.debian.org/News/2013/20130504
 * Renamed "Debian Stable" boxes to "Debian Squeeze 6.0.4"