no need to include JSON atm.
::link in Resource gets processed in the resource_representer.
move to Roar::JSON::JSONAPI. Resource now handles the final document rendering/parsing.
use Resource::Representer to render links: (and linked: later).
collections with links almost work.
collection now simply copies links from Singular.
introduce Representer::for_collection (which will be implemented in representable following @timoschilling's fine PR https://github.com/apotonick/representable/pull/22.