Fix the metadata API for supporting unnanotated properties, services and references. This is needed for the cases where only the SCA assembly descriptor defined these elements (reported by Christophe.)

Refactor the management of dynamic metadata: let the metadata API always return objects which allow retrieving the annotated element and the metadata, be it Java 5 annotations or dynamically set metadata.
See DynAnnotatedElement<T extends AnnotatedElement>.

Move the class loading methods from the ContentClassMetaData to the Util class.

Registered default value of field-based properties with the property controller (issue reported by Christophe.)

TODO : import missing tests from assembly factory examples

* Partial support for contribution zip archive
* Update RELEASE_NOTES and README