Allow Cisco ML2 driver to use the upstream ncclient

[Juergen Brendel]

Currently, the Cisco ML2 driver relies on a specially patched and maintained custom version of the ncclient 3rd party library for communication with various switches.

Changes have been submitted to the upstream ncclient now so that there is no need to maintain a separate version of the ncclient anymore.

To take advantage of the new ncclient version, a small change needs to be made to the Cisco ML2 driver, so that it can detect whether the old (custom) ncclient is installed, or whether the new upstream ncclient is used.

Installation and maintenance will be simplified by not requiring a custom version of the ncclient.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/112175

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/112198

[OpenStack Infra (hudson-openstack)]

Change abandoned by Juergen Brendel (<email address hidden>) on branch: master
Review: https://review.openstack.org/112198
Reason: Git error, sorry.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/112175
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=74c99fb40d4621c6c0915764537dfb54cc6519ca
Submitter: Jenkins
Branch: master

commit 74c99fb40d4621c6c0915764537dfb54cc6519ca
Author: Juergen Brendel <email address hidden>
Date: Wed Aug 6 01:23:52 2014 +0000

    Enabled Cisco ML2 driver to use new upstream ncclient

    The code is still able to handle the old, custom ncclient that
    we used before. It uses the different function signatures
    for the ncclient's connect() function to detect which version
    is installed.

    Change-Id: I09d81b424d86f4cd35ca048507f06471246b91d8
    Closes-Bug: 1352635

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/icehouse
Review: https://review.openstack.org/121567

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/121567
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=ae811df1846be11b0ca72625f67648f6bb9db7d6
Submitter: Jenkins
Branch: stable/icehouse

commit ae811df1846be11b0ca72625f67648f6bb9db7d6
Author: Juergen Brendel <email address hidden>
Date: Wed Aug 6 01:23:52 2014 +0000

    Enabled Cisco ML2 driver to use new upstream ncclient

    The code is still able to handle the old, custom ncclient that
    we used before. It uses the different function signatures
    for the ncclient's connect() function to detect which version
    is installed.

    Change-Id: I09d81b424d86f4cd35ca048507f06471246b91d8
    Closes-Bug: 1352635
    (cherry picked from commit 74c99fb40d4621c6c0915764537dfb54cc6519ca)