Integration of NSX with vCenter

Feature Lead: Andrey Danin
Design Reviewer: Vitaly Kramskikh, Andrew Woodward
Developers: Maxim Datskovskiy
QA: Tanya Dubyk, Aleksandr Kosse

Enable support of vCenter as a Hypervisor and NSX as a networking option in Fuel.
Fuel 5.0 has a limited support of vCenter as a hypervisor and no NSX support at all, but OpenStack an be integrated with both these components. There are two other blueprints already about vCenter support improvements [0] and introducing a basic NSX support [1]. But both features cannot be used simultaneously without some additional work now. If a user has already paired vCenter Cluster and the NSX platform (or multiple pairs vCenter + NSX) she should be able to manage them by OpenStack.
[0] https://blueprints.launchpad.net/fuel/+spec/vcenter-hv-full-scale-support
[1] https://blueprints.launchpad.net/fuel/+spec/neutron-nsx-plugin-integration

Proposed change

After the blueprints [0] and [1] mentioned above would be implemented, there will be a possibility to enable both features deployed simultaneously. It's mostly an administrative work needed because all the manifests will be ready, and we need just to allow a simultaneous use of the features somewhere in Release description.