v2 volume api should return volumenotfound

[jichenjc]

currently, NotFound exception was raised when no volume found in v2 api
this will not be helpful to user especially there is no 'ec2 error code' returned

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/71534

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/79882

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/79882
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=280af85945d7ce8be60135fd364f22e1e8782b87
Submitter: Jenkins
Branch: master

commit 280af85945d7ce8be60135fd364f22e1e8782b87
Author: jichenjc <email address hidden>
Date: Sun Mar 2 13:34:12 2014 +0800

    Raise more information on V2 API volumes when resource not found

    NotFound exception is caught in volumes.py on v2 api
    and raise HTTPNotFound exception but exception information are
    not well specified. This patch adds more information
    to the raised exception.

    Change-Id: I2bd48503460662fcc648b31ade7156059b370f2b
    Closes-Bug: #1275755