Add spec for nsx and vcenter autotests

Enable support of automated acceptance test cases for vCenter and NSX features.
This will allow as to perform full scale acceptance testing of our
features in short time, according to manual test cases of these features
blueprint  nsx-vcenter-system-tests-smoke

Change-Id: Idad4b098f59894ae4624f5071a3f4ff2f807363a
Merge "Add spec for nsx and vcenter autotests"