Fix download url for base ISO
Fix download url for base ISO

mitchellh/vagrant-installers,mitchellh/vagrant-installers,chrisroberts/vagrant-installers,chrisroberts/vagrant-installers,chrisroberts/vagrant-installers,mitchellh/vagrant-installers,mitchellh/vagrant-installers,chrisroberts/vagrant-installers,chrisroberts/vagrant-installers,mitchellh/vagrant-installers,chrisroberts/vagrant-installers,mitchellh/vagrant-installers