notifier_strategy should not be restricted to a specific set of drivers

[Brian Waldon]

glance/notifier/__init__.py defines what the acceptable notifier strategies and aliases that represent them. This prevents users from creating their own strategies, something that would be useful even for testing. We should open it up so a user can specify any of the local strategy aliases, but also be able to provide their own module path.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/9079
Committed: http://github.com/openstack/glance/commit/2a61bf38ff6dae16083145e6f27d66731d5c3271
Submitter: Jenkins
Branch: master

commit 2a61bf38ff6dae16083145e6f27d66731d5c3271
Author: Brian Waldon <email address hidden>
Date: Wed Jun 27 13:49:15 2012 -0700

    Allow CONF.notifier_strategy to be a full path

    Rather than limit the notifier_strategy to a list of internal
    drivers, we should also allow a user to supply a full path
    to a custom driver. This is going to help us functionally test
    our notification system without having to ship a fake driver.

    Fixes bug 1018638

    Change-Id: Ib1cae7b979dabfaa6b8b5aa59719aad2ac12d169