The Actionbar widget currently implements the View interface (ui-api) instead of having the ActionbarPresenter produce a ViewImpl that uses the Widget internally. There are also further issues that do not fall inline with the MVP pattern.

• The widget should be ui-api agnostic.
• The ActionbarPresenter should inject the ActionbarView
  • remove direct instantiations of the ActionbarPresenter along the way
• The ActionbarFactory (produces a widget based on config) should be inlined inside the ActionbarPresenter.
• The ActionbarPresenter.Listener interface shouldn't be used to get action label and icon, instead the map of ActionDefinitions should be passed into the presenter upon startup.