Add support for the Nexus 1000V into the Cisco Plugin.

This will enable the Cisco Nexus 1000V to integrate with the Cisco plugin and be used to drive the realization of Quantum constructs.
Network profile and Policy profile are introduced as extended quantum resources, while n1kv:profile_id is introduced as an extended
attribute for network and port objects. Necessary changes to the Cisco plugin are made to accomodate Nexus 1000V as a configurable
vswitch plugin.

Implements: blueprint cisco-plugin-n1k-support
Change-Id: I951e10c57d74c935fca8754c0e21e1ac9df35704