Merge remote-tracking branch 'origin/feature/qos' into merge-branch

Merge remote-tracking branch 'origin/feature/qos' into merge-branch

Note to reviewers: gerrit diff for merge patches is very limited, and
leaving comments in global section won't scale, so please comment here:

https://etherpad.openstack.org/p/qos-merge-back-review

This merge commit introduces QoS feature into Liberty release of
Neutron.

The feature is documented in: doc/source/devref/quality_of_service.rst
included with the merge patch.

It includes:

- QoS API service plugin with QoS policy and QoS bandwidth limit
  (egress) rule support;
- core plugin mechanism to determine supported rule types, with its ML2
  implementation;
- new agent extension manager;
- QoS agent extension with pluggable backend QoS drivers (Open vSwitch
  and SR-IOV support is included).

To extend network and port core resources with qos_policy_id attribute,
a new ML2 extension driver (qos) was introduced that relies on the QoS
core resource extension (the idea is that eventually we'll get a core
resource extension manager that can be directly reused by core plugins).

Agent-server interaction is based on:

- get_device_details() method that is extended with qos_policy_id;
- a new push/pull mechanism that allows agents and servers to
  communicate using oslo.versionedobjects based objects sent on the
  wire.

The merge includes the following types of test coverage:

- unit tests;
- functional tests for OVS agent, QoS agent extension, and low level
  ovs_lib changes;
- API tests to cover port/network qos_policy_id attribute and new QoS
  resources.

The client changes can be found at:

* https://review.openstack.org/189655
* https://review.openstack.org/198277

The team also prepared fullstack test but it needs to wait for client
merge before it can pass in the gate:

* https://review.openstack.org/202492

Gerrit does not show diff for merge changes that did not result in any
conflict, so to facilitate review, rely on the following steps:

- fetch the patch locally
- git fetch origin
- git diff origin/master...

This merge also disables qos extension API tests until the service is
enabled in master gate.

Local changes apart from conflicts:
- updated down_revision for qos migration to reflect master expand head;
- disabled qos API tests with gate_hook.sh until we have it enabled in
  master gate;
- bumped oslo.versionedobjects requirement to reflect what is in
  openstack/requirements' global-requirements.txt

DocImpact
APIImpact
Partially-Implements: blueprint quantum-qos-api
Partially-Implements: blueprint ml2-qos
Partially-Implements: blueprint ml2-qos-ovs-bwlimiting
Partially-Implements: blueprint ml2-sriov-qos-with-bwlimiting
Change-Id: I92916d0e391791187e9a25ff172fb4b3504857b1