clean default widget

vendor/built_in_modules/announcement/app/models/bulletin.rb

@@ -77,11 +77,6 @@ class Bulletin
     string :bulletin_category_id
     end
   
-
-  def postdate_with_format
-    self[:postdate].strftime("%m/%d/%Y")
-  end
-
   def bulletin_category_with_title
     self.bulletin_category.title
   end

vendor/built_in_modules/announcement/config/locales/zh_tw.yml

@@ -18,4 +18,4 @@ zh_tw:
     default_widget:
         bulletin_category_with_title: 分類
         title: 標題
-        postdate_with_format: 張貼日期
+        postdate: 張貼日期