Removed Faces Scaffold addon from Core.

This addon is now present in the JavaEE addon.
Hence, we'll include it just once.
Fixed generation logic to use JavaResources instead of JavaClasses.

This ensures that the scaffold provider design to use Resource
instances is upheld. It removes the restriction on using JavaClass
instances to represent 'scaffoldable' items for a scaffold
provider.
Modified ScaffoldProvider API.

This adds UIContext as a parameters to the getSetupFlow() and
getGenerationFlow() methods of the ScaffoldProvider interface.
This ensures that the selected Project instance can be accessed
in these methods.