Signal on configuration completion.

The completion-handle comes from Heat Metadata e.g.
    Metadata:
      completion-handle: {Ref: StackCompleteHandle}

Change-Id: I7202e94a2d327c4e5d3023b02d7c0417ffd0e354
Merge "Signal on configuration completion."
Notify IRC when tripleo-cd completes.

This will let us detect failures and dogpile on them, crude but effective.

Change-Id: If923f20d61e024066d83d06e14fc1584368f8392