kill register_appobject_class method, simplifying autoregistration. Update test accordingly (test which manually registers object should also properly call there __register__ method). Drop the disable-appobjects config file entry: no one used it since its introduction years ago.

This directory is where you should put your lax components.

For your application to actually use a component, you also 
have to modify the ``INCLUDED_COMPONENTS`` variable in 
the ``custom.py`` module.