Brick's iser.py has dependency on cinder

[Walt Boring]

brick/iser/iser.py has dependency on cinder exception.py as well as volume_utils.

Nothing in brick can have a dependency on cinder, or it won't work in other projects (nova, glance)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/40984

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/40984
Committed: http://github.com/openstack/cinder/commit/d1d6b808afec4a4d74d004dc48832eaaf1b415b1
Submitter: Jenkins
Branch: master

commit d1d6b808afec4a4d74d004dc48832eaaf1b415b1
Author: Walter A. Boring IV <email address hidden>
Date: Thu Aug 8 15:29:54 2013 -0700

    Remove Brick iser dependency on cinder

    This patch removes the brick iser.py's dependency
    on cinder exceptions and volume_utils.
    This required moving some exceptions out of cinder's
    exception.py that the iser.py raises. Also had
    to create a BrickException and refactor existing
    brick exceptions to use the new BrickException model.

    Fixes Bug #1210312

    Change-Id: I672375807fed4952e5321fbcd9b57b9ef369f68f