Multi-segment and trunk support for the Cisco N1Kv Plugin

This patch adds vlan and vxlan trunk support in the
Cisco N1Kv plugin. It also adds support for multi-segment
networks for bridging vlan networks with vxlan networks.

Change-Id: Ibecbbfbce1eb4d18ef6a1bc5250622b9ae87d39c
Implements: blueprint multi-segment-and-trunk-support-cisco-nexus1000v