Document service factory configuration

Need to enhance the documentation about how and why to configure the service factory for endpoints.

Basically you can set the data binding and some other things which relate to the service model creation into the service factory bean.
It will give the users more flexibility when they want to change some internal service model states.
The restful_service.xml is an example of setting the wrapped property which will affects the bear or wrapped message creation.
You can find more information by walking through the JaxWsServiceFactoryBean, RefelectionServiceFactoryBean.