Exclude 'vnet' interfaces from being candidates for running a dhcp client.
Exclude 'vnet' interfaces from being candidates for running a dhcp client.

Vnet interfaces are not supported by the dhcp client.

Bug #1731871

Change-Id: I8c0d6b0885f7e5fac94f78c8d6b6a6bf198ff424
Signed-off-by: Wojciech Dec <ce6448a6b6217030554076da1d3c92bbd1cfea3a@cisco.com>

openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates