Resolving of ServletExceptions via the configured HandlerExceptionResolvers

Implemented the class ExceptionResolverErrorController, tries to resolve the
root-cause of a ServletException via the configured HandlerExceptionResolvers.

To do so, the class mimics the initialization of the configured
HandlerExceptionResolvers, that the DispatcherServlet executes, because,
unfortunatly, the DispatcherServlet does not make the configured resolvers
available.