workaround for coraid appliance multiply requests

[Nikolay Sobolevsky]

The Coraid ESM appliance could corrupt some request after simultaneous massive request in the same session.
Temporary workaround is to call every appliance command in the new session and connection.

The current coraid.py file very sensibly re-uses a single rest client object for subsequent requests. Unfortunately, ESM back-end doesn't support using the same authenticated session token (JSESSIONID) for concurrent requests, due to concurrency limitations.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/43259

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/43259
Committed: http://github.com/openstack/cinder/commit/f730adaeec98baea419b3b159fff1e1127d266ac
Submitter: Jenkins
Branch: master

commit f730adaeec98baea419b3b159fff1e1127d266ac
Author: Nikolay Sobolevskiy <email address hidden>
Date: Wed Aug 21 14:15:08 2013 +0400

    Use a new rest client for every Coraid ESM command

    It's workaround for the session corruption bug
    in the ESM Appliance.

    fix bug #1214433

    Change-Id: Ie844f3c95675c4d734390c23ed2d421c159ce8a7