Neutron-api charm can't enable qos

I've been following https://docs.openstack.org/mitaka/networking-guide/config-qos.html and have a set of changes ready to land. I've added support for Mitaka+

The changes do the following:

1) Add enable-qos option to the neutron-api charm. If enable-qos is set then neutron.services.qos.qos_plugin.QoSPlugin is added to service_plugins in neutron.conf locally. The neutron-plugin-api-relation has also been updated to send the enable-qos
2) Charmhelper update to read the enable-qos setting on the neutron-plugin-api-relation and update NeutronAPIContext
3) Update neutron-openvswitch to set extensions='qos' in openvswitch_agent.ini if qos is enabled
4) Update neutron-gateway to set extensions='qos' in openvswitch_agent.ini if qos is enabled

If tested setting max-kbps and max-burst-kbps qos settings and monitoring iperf. I've tested applying the limits to both an instances' qvo interface on the compute node and a networks tap interface on the gateway.

Fix proposed to branch: master
Review: https://review.openstack.org/491538

Reviewed: https://review.openstack.org/491538
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-api/commit/?id=a8e6824e3a520b8bbacd7bc3339d945124928f03
Submitter: Jenkins
Branch: master

commit a8e6824e3a520b8bbacd7bc3339d945124928f03
Author: Liam Young <email address hidden>
Date: Mon Aug 7 17:05:28 2017 +0100

    Add QoS support

    This patch adds the enable-qos option to the charm. If enable-qos is
    set then neutron.services.qos.qos_plugin.QoSPlugin is added to
    service_plugins in neutron.conf locally. The
    neutron-plugin-api-relation has also been updated to send the
    enable-qos option to charms connected over that relation (for
    example neutron-openvswitch and neutron-gateway).

    As part of this some of the logic for setting service_plugins was
    removed from the neutron.conf and placed in the NeutronCCContext.

    This patch is based on the steps in:
    https://docs.openstack.org/mitaka/networking-guide/config-qos.html

    Change-Id: I1beba9bebdb7766fd95d47bf13b6f4ad86e762b5
    Partial-Bug: #1705358

Reviewed: https://review.openstack.org/491539
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-openvswitch/commit/?id=cf383ecd3fa0aab7bf409885db808d1510152c24
Submitter: Zuul
Branch: master

commit cf383ecd3fa0aab7bf409885db808d1510152c24
Author: Liam Young <email address hidden>
Date: Mon Aug 7 16:58:52 2017 +0100

    Add QoS support

    This patch adds support for reading the 'enable-qos' setting from the
    neutron-plugin-api relation and adding 'qos' to the extension_drivers setting
    if it is True. This is part of a wider set of changes to support QoS across the
    neutron charms.

    A charmhelper sync was performed to pull in the QoS update to the
    NeutronAPIContext.

    Note: Amulet tests will fail until the corresponding neutron-api change
    lands

    Depends-On: I1beba9bebdb7766fd95d47bf13b6f4ad86e762b5
    Change-Id: I9d857a4f2a25c6080963a0f3f6e6592c0a77d133
    Partial-Bug: #1705358

Reviewed: https://review.openstack.org/491540
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-gateway/commit/?id=a5f92548c0a08566386f9c89863fe926696eb32c
Submitter: Zuul
Branch: master

commit a5f92548c0a08566386f9c89863fe926696eb32c
Author: Liam Young <email address hidden>
Date: Mon Aug 7 17:04:33 2017 +0100

    Add QoS support

    This patch adds support for reading the 'enable-qos' setting from the
    neutron-plugin-api relation and adding 'qos' to the extension_drivers setting
    if it is True. This is part of a wider set of changes to support QoS across
    the neutron charms.

    The amulet tests were missing the neutron-api to neutron-gateway relation this
    has been added in. A side-effect of this is that the l2-population setting is
    now properly being set to True so tests were updated to expect that.

    A charmhelper sync was performed to pull in the QoS update to the
    NeutronAPIContext.

    Note: Amulet tests will fail until the corresponding neutron-api change
    lands

    Depends-On: I1beba9bebdb7766fd95d47bf13b6f4ad86e762b5
    Change-Id: I6dc71a96b635600b7e528a9acdfd4dc0eded9259
    Partial-Bug: #1705358