Object inequality evaluation syntax nits

[Zhongyue Luo]

There are some lines in cinder where instead of "if X is not Y", it uses "if not X is Y"

Since "is not" seems to be the consensus and is more intuitive, object inequality evaluations should use "is not"

$ grep -R " not " cinder | grep " is " | grep -v " is not " | grep -E ":\W*if" |wc -l
6
$ grep -R " not " cinder | grep " is " | grep -E ":\W*if" |wc -l
108

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/20866

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/20866
Committed: http://github.com/openstack/cinder/commit/8960e4d33c73d79778aa02cfed0c7691a3b7e158
Submitter: Jenkins
Branch: master

commit 8960e4d33c73d79778aa02cfed0c7691a3b7e158
Author: Zhongyue Luo <email address hidden>
Date: Thu Jan 31 10:31:51 2013 +0800

    Fixes "is not" usage

    Fixes bug #1110987

    Change-Id: Iafa9fc548deaf03c229cc9144d85e6c68b3101be