Add seperate 'no items' message for defaults

Closes #53

app/helpers/application_helper.rb

@@ -179,7 +179,7 @@ module ApplicationHelper
 
   def render_no_items
     tag.tr id: :no_items do
-      tag.td t("#{controller_name}.no_items"), colspan: 10, class: 'hint'
+      tag.td t("#{controller_path.tr('/', '.')}.no_items"), colspan: 10, class: 'hint'
     end
   end
 

config/locales/en.yml

@@ -75,6 +75,7 @@ en:
       success: Deleted unit "%{unit}"
   default:
     units:
+      no_items: There are no importable defaults or exportable units.
       unit:
         delete: Delete
         export: Export