FIX: EPUB::Book::Features.cover_image, consistently gets cover image information,
     not backwards compatible, now returns a Hash in the likes of:
     { :file_name=>"cover.jpg", :media_type=>"image/jpeg", :file_contents=> "\xFF\xD8\xFF\xE0\x00\x10JFIF\x00\x01\..." }

FOX: Metadata.Metas now correctly returns content for <Meta> tags.