updated URL to ISO for Debian 7.5.0;
updated URL to ISO for Debian 7.5.0;

mirage/mirage-vagrant-vms,sjfloat/mirage-vagrant-vms,yifanz/mirage-vagrant-vms,sjfloat/mirage-vagrant-vms,yifanz/mirage-vagrant-vms,mirage/mirage-vagrant-vms,englishm/vagrant-xen,englishm/vagrant-xen