Ceilometer should record nova instances state

[François Charlier]

Currently ceilometer does not record nova instances state (vm_state, power_state, task_state).

A cloud owner might want to have different rates given the instance state (when it is running, paused, suspended or errored for example).

I suggest that:

* The state of the instance should be inserted in instance metadata when receiving events

* All events should be recorded and let the owner the responsibility to choose which instance states are interesting to him

* The documentation should recommend enabling 'notify_on_any_change' and 'notify_on_state_change' in nova.conf

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/33057

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/33057
Committed: http://github.com/openstack/ceilometer/commit/00531f9de040f43c643dd843ada986cfbcf91e87
Submitter: Jenkins
Branch: master

commit 00531f9de040f43c643dd843ada986cfbcf91e87
Author: Julien Danjou <email address hidden>
Date: Fri Jun 14 13:51:39 2013 +0200

    Unify Counter generation from notifications

    This will make sure we don't lose any metadata information from
    notifications into the Counter/samples we publish.

    This is part of fixing bug #1187833 and bug #1187843

    Change-Id: I315581907be1dcec33f43a5d5fd7b7876a7889f6
    Signed-off-by: Julien Danjou <email address hidden>