Added correct equals(…)/hashCode() methods to PagedResource, PageMetadata. Polished toString() methods of ResourceSupport, Resource, Resources and PagedResources. Added factory method to PagedResources to easily create a plain instance from a set of entities.
Introduced Resource and Resources value objects. The former captures single entity instances but adds links to it. The latter does the same for a collection of entities. Added SPI interfaces ResourcePostProcessor and ResourcesPostProcessor to allow manipulating Resource and Resources instances.
Improve ResourceAssemblerSupport by introducing a dedicated method instead of an overload. Got rid of EntityId in the course. ControllerLinkBuilder now inspects type hierarchy for @RequestMapping annotations instead of the class only. Made links list in ResourceSupport final. Polished variable names and JavaDoc.
