Exceptions that get returned via REST api should have more user friendly messages

[Joe Gordon]

Exceptions in nova/exception.py that get returned via REST api should have more user friendly (non-admin and non-dev) messages.

For example

 class InstanceRecreateNotSupported(Invalid):
     msg_fmt = _('Instance recreate is not implemented by this virt driver.')

Assuming that exception gets returned via the REST API, a user shouldn't have to know what a 'virt driver' is, that is a backend concept that we should be hiding.

Instead this exception should say something like 'Instance recreate is not supported'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/67755

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/67755
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=8cc59d2084a8b1129929a162b753d4ca407018e7
Submitter: Jenkins
Branch: master

commit 8cc59d2084a8b1129929a162b753d4ca407018e7
Author: lizheming <email address hidden>
Date: Mon Jan 20 11:10:37 2014 +0800

    Make exception message more friendly

    Exceptions that get returned via REST api
    should have more user friendly message,
    users shouldn't have to know backend concept.
    more detail,see bug.

    Change-Id: Idc20680e46c36fa3441838177ce61b6f5e1d2979
    Closes-Bug: #1263204