Re #176: Optimize EDM export job.
Re #176: Adjust sweepers for cached EDM RDF/XML.
Re #176: Adjust EDM export to non-flat RDF/XML structure.
Re #176: Re-order RDF/XML elements in EDM export.
Re #176: Rake task to clear cached contribution EDM RDF/XML.
Re #176: Add xml:lang attribute to edm:Concept > skos:prefLabel elements.
Re #176: Remove garbage collection trigger in (optimized) contribution export.
Re #176: Rake task to clear cached EDM for attachments.