Update template file ta-debian-7-wheezy.json
Update template file ta-debian-7-wheezy.json

* Fix Debian ISO URL (version 7.2.0 no longer available).
* Update ISO checksums.
* Fix builder names: since packer version 0.5.0, virtualbox and vmware
builders are renamed to virtualbox-iso and vmware-iso (see
https://github.com/mitchellh/packer/blob/master/CHANGELOG.md#050-1230201
3).

tech-angels/packer-templates,greyia/packer-templates,lukeadams/packer-templates,yoshi-naoyuki/packer-templates,lazyfrosch/packer-templates,danielmt/packer-templates