[Launch Instance Fix] Enhancing wizard widget

[Shaoquan Chen]

Add some events to Wizard widget to provide hooks for logic in model(s)
and controller(s) for each step.

New wizard events added are:
- ON_INIT_SUCCESS
- ON_INIT_ERROR
- ON_SWITCH
- BEFORE_SUBMIT
- AFTER_SUBMIT

Some features in Launch Instance work flow can take advantage of this
infrastructure change:
- Refreshing page on `AFTER_SUBMIT` event.
- Lazy data sync and validation on `BEFORE_SUBMIT` event.
- Dynamical showing/hiding optional steps/content according to async check for availability of certain services on `ON_INIT_SUCCESS` event.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/165475

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165475
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=39ba4d19da95b5148ff3b0e963fee9ccf746d3a9
Submitter: Jenkins
Branch: master

commit 39ba4d19da95b5148ff3b0e963fee9ccf746d3a9
Author: Shaoquan Chen <email address hidden>
Date: Wed Mar 18 08:49:24 2015 -0700

    [Launch Instance Fix] Enhancing wizard widget

    1) Add some events to Wizard widget to provide hooks for logic in model(s)
    and controller(s) for each step.

    New wizard events added are:
    - ON_INIT_SUCCESS
    - ON_INIT_ERROR
    - ON_SWITCH
    - BEFORE_SUBMIT
    - AFTER_SUBMIT

    Some features in Launch Instance work flow can take advantage of this
    infrastructure change:

    - Refreshing page on `AFTER_SUBMIT` event.
    - Lazy data sync and validation on `BEFORE_SUBMIT` event.
    - Dynamical showing/hiding optional steps/content according to async check for
      availability of certain services on `ON_INIT_SUCCESS` event.

    2) Add a new feature to check readiness for each step that provides a optional `checkReadiness`
    method. Each such a method should return a promise. When this method is
    provided with the step, the `ready` property of the step will be set to
    `false` until the promise gets resolved. If no `checkReadiness` method
    provided, the `ready` property of the step will be set to `true` directly.

    This it useful for those work flow where some step may be optional and
    should be showing to UI conditionally and the check for the condition
    is an asynchronous operation.

    Co-Authored-By: Brian Tully <email address hidden>
    Closes-Bug: 1433674
    Change-Id: I556e263f4c701a378452b4397585f1b4d8abb763