3.0 - WIP - Added accessor method getView() to ViewVarsTrait.

Let me know if this seems worth pursing.

`AppView` allows setting defaults and then in controller you would use `$this->getView()->foo` to modify stuff as needed. `Controller::$helpers` and similar view related properties would be gone.
The cachehelper replacement won't need requestAction() as a real proxy cannot set internal parameters like bare. Instead of relying on bare requestAction users can use the 'ajax' layout. Automatically switching to the ajax layout on requestAction() requests could even be done by RequestHandlerComponent.