Fix execute_command for ovftool on virtualbox
Fix execute_command for ovftool on virtualbox

Signed-off-by: Abhijit Hiremagalur <6b8f12da63e0791f9a1397d0839e407f10b8af40@pivotallabs.com>

cloudfoundry/bosh-packer-templates,voelzmo/bosh-packer-templates,cloudfoundry/bosh-packer-templates,Altoros/bosh-packer-templates,voelzmo/bosh-packer-templates,Altoros/bosh-packer-templates