Add ability for deployments to include jbossws-entities.properties

Currently entity resolution is very limited in JBossWS Native. You must override the entire jbossws-entities.properties file included in jbossws-native-core.jar system-wide to add your own entities. This change would allow applications to add entities to their own deployment's jbossws-entities.properties file without making the changes system-wide and without having to include all the entries already in the file included in jbossws-native-core.jar