Fix missing availability_zone in dhcp and l3 conf
Fix missing availability_zone in dhcp and l3 conf

Now availability_zone attribute can be defined in dhcp-agent
and l3-agent. But the config had not generated in dhcp_agent.ini
and l3_agent.ini

This patch add availability_zone in base_agent_opts. That will
apply in dhcp and l3 agent conf.

Closes-Bug: #1589745
Change-Id: I9fdc39b1f9abd48a4b55e0a917e41bf68be56595

openstack/neutron,huntxu/neutron,mahak/neutron,mahak/neutron,igor-toga/local-snat,cloudbase/neutron,eayunstack/neutron,eayunstack/neutron,sebrandon1/neutron,sebrandon1/neutron,igor-toga/local-snat,cloudbase/neutron,mahak/neutron,openstack/neutron,openstack/neutron,huntxu/neutron,noironetworks/neutron,noironetworks/neutron