* add debian/d-i/squeeze/example-preseed.txt
   - example from http://www.debian.org/releases/squeeze/example-preseed.txt
 * add debian/d-i/wheezy/example-preseed.txt
   - example from http://www.debian.org/releases/wheezy/example-preseed.txt
 * clean up debian/d-i/squeeze/preseed.cfg and debian/d-i/wheezy/preseed.cfg based on example-pressed.txt