OSTF: Add a set of automated tests for NSX and vCenter for Fuel for OpenStack

Feature Lead: Andrey Danin QA: Tanya Dubyk, Aleksandr Kosse 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 in this document: https://docs.google.com/a/mirantis.c...