Add KonferenzRemotingSpringConfig and VortragRemotingSpringConfig

Transform spring-konferenz-remoting-config.xml and
spring-vortrag-remoting-config.xml into KonferenzRemotingSpringConfig and
VortragRemotingSpringConfig while the class-path-scanning approach hasn't
landed yet.
Properly wire BenachrichtigeReferentenBeiKonferenzAenderung bean