Nexus RESTAPI Client Improvements

[Carol Bouchard]

Implement https
reuse cookie until it fails.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/524223

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/524223
Committed: https://git.openstack.org/cgit/openstack/networking-cisco/commit/?id=cd210d2711fb2435840526da124572c9efd16d01
Submitter: Zuul
Branch: master

commit cd210d2711fb2435840526da124572c9efd16d01
Author: Carol Bouchard <email address hidden>
Date: Thu Nov 30 10:46:10 2017 -0500

    Nexus RESTAPI Improvements

    A few improvements have been added to the Nexus RESTAPI Client
    Driver. First the driver now supports https. This causes
    communication with the Nexus device to be encrypted. This also
    allows for certificate verification. For the latter capability,
    the default on the new configuration option 'https_verify' is
    initially set to False (insecure) but will be set to True (secure)
    in the next Cisco release 6.0.0. For testing purposes, a locally
    generated certificate can also be provided using the config
    parameter 'https_local_certificate'.

    To improve performance, the same cookie will be used in requests until
    the Nexus device returns a status_code of 403. When this is detected,
    an attempt to refresh the cookie will occur and upon successful
    receipt of a new cookie the original request will be re-sent.

    Change-Id: I87b4c91f8f8cfbcb070f7e615b7a12537fb2d6d3
    Closes-bug: #1735295