ISIS-493: @DomainService annotation, auto-registration.

NB: in doing this work, identified that Simple Objects 1.5.0 example app (and therefore archetype) has an issue.... need to register ClassDiscoveryServiceUsngReflections in its isis.properties file.
ISIS-493: completing @DomainService auto-registration

- now has menuOrder() and also repositoryFor() attributes (both optional).
- refactored the way that services from configuration are read in so that can mix-and-match services from both configuration and via annotation
- marked all the non-JDO services (that have no hard dependencies on JDO services) as being @DomainService (in core-applib, core-metamodel and core-runtime).
- updated the simple and todo apps to use this new feature.
Also:
- bumped pom.xml parent for some components

NB: no changes to integration test infrastructure... still have to register each programmatically.