listen for instance resize events

[Eoghan Glynn]

When an instance is resized, the RAM and/or cores usage may change.

We will catch the resource usage change eventually in the compute.instance.exists notification, however this will be delayed by up to periodic_interval seconds (defaults to 60s, but could be configured higher).

However we could eagerly detect the change by catching 'compute.instance.finish_resize.end' and corresponding confirm/revert notifications.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/18966

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/18966
Committed: http://github.com/openstack/ceilometer/commit/444978f16aca246776fcdbfa521fa1e6f689d0dd
Submitter: Jenkins
Branch: master

commit 444978f16aca246776fcdbfa521fa1e6f689d0dd
Author: Eoghan Glynn <email address hidden>
Date: Fri Jan 4 16:17:18 2013 +0000

    Handle finish and revert resize notifications.

    Fixes bug 1057571

    Ensure that the modified instance type is reflected in the
    metering data in a more timely fashion than would be allowed
    by the default pollster frequency, or the cadance of the
    compute.instance.exists notifications.

    Change-Id: I34f01eebddfe9732d5bf69c331a0d8a63a8025ca