NSX|V: add in exclusive DHCP support

[OpenStack Infra]

https://review.openstack.org/444638
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/vmware-nsx" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit c33810b865324ad433fbcd9a89fbbf9f75ee32f1
Author: Gary Kotton <email address hidden>
Date: Sun Mar 12 01:20:14 2017 -0800

    NSX|V: add in exclusive DHCP support

    Via the configuration variable exclusive_dhcp_edge enable a tenant
    to create a exclusive DHCP edge. This can be global or via AZ.

    DocImpact

    Change-Id: Ia5220302114d73fa89b3f3ea86141cb3208fe885