WBE is not proxying all bound task handlers

[Joshua Harlow]

Currently the WBE will proxy back 'update_progress' status calls to a callback function located wherever the engine is running. This is good. It thought does not appear to be proxying back any custom attached handlers that were also attached to a task for any task specific events that are not 'update_progress' (this is bad). It also appears to be only proxying back to the handler proved to _execute_task() or _revert_task() and not to any other customized handlers that are attached to the task before being submitted for execution (this is bad).

We should fix this like it has been fixed in https://review.openstack.org/#/c/121280/ and perform a similar proxying mechanism (obviously not the same since the WBE engine does not run in local processes) to resolve this issue.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/141534
Committed: https://git.openstack.org/cgit/openstack/taskflow/commit/?id=1f4dd72e6e859f3820de5e68ece2d09c15a18b70
Submitter: Jenkins
Branch: master

commit 1f4dd72e6e859f3820de5e68ece2d09c15a18b70
Author: Joshua Harlow <email address hidden>
Date: Fri Dec 12 15:57:53 2014 -0800

    Use the notifier type in the task class/module directly

    Instead of having code that is some what like the notifier
    code we already have, but is duplicated and is slightly different
    in the task class just move the code that was in the task class (and
    doing similar actions) to instead now use a notifier that is directly
    contained in the task base class for internal task triggering of
    internal task events.

    Breaking change: alters the capabilities of the task to process
    notifications itself, most actions now must go through the task
    notifier property and instead use that (update_progress still exists
    as a common utility method, since it's likely the most common type
    of notification that will be used).

    Removes the following methods from task base class (as they are
    no longer needed with a notifier attribute):

    - trigger (replaced with notifier.notify)
    - autobind (removed, not replaced, can be created by the user
                of taskflow in a simple manner, without requiring
                functionality in taskflow)
    - bind (replaced with notifier.register)
    - unbind (replaced with notifier.unregister)
    - listeners_iter (replaced with notifier.listeners_iter)

    Due to this change we can now also correctly proxy back events from
    remote tasks to the engine for correct proxying back to the original
    task.

    Fixes bug 1370766

    Change-Id: Ic9dfef516d72e6e32e71dda30a1cb3522c9e0be6