camel-cxf - CxfRsProducer should support invoking methods with no parameters

See user forum
http://fusesource.com/forums/thread.jspa?messageID=9722&#9722

In the future we should rework the camel-core a bit to offer an API for discovering methods which is based on the bean component with its bean parameter binding support which is much more advanced than the custom code in CxfRsProducer.