Add the Performance Management Threshold CLI to support AutoScale.
The Performance Management Threshold API is based on ETSI NFV-SOL
002 v3.3.1 and ETSI NFV-SOL 003 v3.3.1, which is Version "2.0.0"
API of Tacker.
Implements: blueprint support-auto-lcm
Change-Id: Idd313d6abe47dfa41fc86ddc614d00f99f3fc3b2