Send parameterized vcenter and exsi version to setup-testbed robot file instead of hardcoded ones

[lmalvins]

Actually, the setup-testbed.robot and vic-common.robot file have hardcoded versions of the vcenter and exsi to deploy on.

It is more practical and reusable if we declare these versions as variables and injects them on the Jenkins job, even more for future sanity checks which runs against different vcenters and/or esxi versions.