Nicira Plugin need to work with different versions of the NVP API

[Salvatore Orlando]

The Nicira plugin is currently targeting a specific version of the NVP API.
We need to ensure the same plugin can work even with different versions of the NVP controllers.

This is important in order to allow NVP to be upgraded independently of Quantum.

Changes should be limited to nvplib, the module for interfacing with the nvp api.
This could be achieved, for instance, using some for of monkey patching to methods whose implementation changes from one version to another.

Note: This cannot possibly be a general solution, but will work perfectly when there are minor changes in the NVP API that do not require any change in the Quantum logic

[Salvatore Orlando (salvatore-orlando)]

Setting importance to 'medium'.
The plugin maintainer (arosen) will set definitive important and milestone target.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/22037

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/22037
Committed: http://github.com/openstack/quantum/commit/b17bd081a16513307e5b8dd8a2d738173050ff93
Submitter: Jenkins
Branch: master

commit b17bd081a16513307e5b8dd8a2d738173050ff93
Author: Salvatore Orlando <email address hidden>
Date: Mon Jan 28 16:41:53 2013 -0800

    Allow nicira plugin to handle multiple NVP API versions

    Bug #1126352

    This patch introduces a simple framework for enabling
    nvlib to call the appropriate routine according to the
    current version. To this aim, we leverage the 'server' header
    which is returned by every NVP API calls (except login/logout).
    The patch also accounts for the changes introduced in NVP 3.0

    Change-Id: Ief3a6f2b5b99ea33548353ce3bee3fa23e42752f