Description of problem:
When we activate DVR setup, compute node should have an interface in external network (eth2 should be added to br-ex).
Currently there is no configuration that does that and the compute node can not communicate with external network. 

Version-Release number of selected component (if applicable):
openstack-tripleo-heat-templates-5.0.0-0.20161008015357.0d3e3e3.1.el7ost.noarch
openstack-heat-templates-0.0.1-0.20161004223740.f123aa1.el7ost.noarch


How reproducible:
100%

Steps to Reproduce:
1.install openstack with ospd + dvr activating yaml file ( /usr/share/openstack-tripleo-heat-templates/environments/neutron-ovs-dvr.yaml)
2.create router, external and internal networks, configure router with gateway and internal network port. Create FIP
3. Boot VM and assign it with FIP

Actual results:
No ping to 8.8.8.8 from VM.
After investigation we saw that the ping from fg interface on FIP-namespace cant reach external network. 

workaround: 
Compute node: 
ovs-vsctl add-port br-ex eth2 


Expected results:
Ping should be successful 

Additional info:
We need a yaml that will configure compute networking properly for DVR .