tableheader is 'none' if no header can be applied

git-svn-id: https://dev.finn.de/svn/cockpit/branches/reporting_merge@1478 7926756e-e54e-46e6-9721-ed318f58905e

app/helpers/reporting_helper.rb

@@ -54,7 +54,7 @@ module ReportingHelper
   def show_field(key, value)
     @show_row ||= Hash.new { |h,k| h[k] = {}}
     @show_row[key][value] ||= begin
-      return "" if value.blank?
+      return l(:label_none) if value.blank?
       case key.to_sym
       when :activity_id               then mapped value, Enumeration, :caption_material_costs
       when :project_id                then link_to_project Project.find(value.to_i)