Add a Node Profile support to the API

Node Profiles are needed concept for Resource Classes in order to assure SLA. In node profile, operator specifies Hardware Requirements and various restrictions based on described hardware (e.g. max number of instances of given flavor), so that service level can be assured. We need to add this concept to the API. Detailed description and supportive wireframes will follow in whiteboard.

This is too fine grained: https://wiki.openstack.org/wiki/Blueprints - blueprints are for significant features (vs the individual steps in planning things where etherpad is great)