ML2 plugin should enable trunk service plugin by default

[Brent Eagles]

The VLAN aware VMs aka trunk port feature was added in Newton. The functionality is contained in an optional service plugin and may be enabled by default during deployment as it will not affect users who are not using this feature.

To enable, simply add "trunk" to the existing list of service_plugins.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/363083

[Assaf Muller (amuller)]

VLAN aware VMs is a high profile Neutron feature that is arriving late in the Newton cycle, it'd be neat to have it configured/enabled out of the box via TripleO and not miss a cycle.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/363083
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=288088a13319cf486d1f34a11b61843c7cc89d27
Submitter: Jenkins
Branch: master

commit 288088a13319cf486d1f34a11b61843c7cc89d27
Author: Brent Eagles <email address hidden>
Date: Tue Aug 30 14:49:46 2016 -0230

    Add trunking plugin to list of default ML2 service plugins

    This patch adds the 'trunk' service plugin to the list of plugins
    enabled by default when using the ML2 plugin. This service plugin
    enables the VLAN-aware-VM feature in Neutron.

    Closes-Bug: 1618570
    Change-Id: Ic55706d05adc9fa8baa2828ae4c939c11deb2083