def update_categories
      h = {}
      Category.all.each do |category|
        next if ["rating", "year", "unknown"].include?(category.name)
        h[category.name] = category.tags.collect { |tag| tag.name }
      end
      @config[:categories] = h
    end
def update_categories
      h = {}
      Category.all.each do |category|
        next if ["rating", "year", "unknown"].include?(category.name)
        h[category.name] = category.tags.collect { |tag| tag.name }
      end
      @config[:categories] = h
    end
update config file with tag category list and association from category to tag name,
 so to not lose the association next time the catalog is rebuilt (updated)