Fix MediaColumn the condition of skipping refresh_attachments callback

lib/whaleback/media_column.rb

@@ -9,20 +9,20 @@ module Whaleback
       def media_url_column column, column_parse=Proc.new(&:itself)
         collection = "#{column}_attachments"
         has_many collection.to_sym, ->{ where(column_name: column) }, class_name: 'Whaleback::Media::Attachment', as: :attached, dependent: :destroy 
-        after_save {
-          refresh_attachments(column_parse.call(send(column)), column) if "saved_change_to_#{column}?".to_sym
+        after_save if: "saved_change_to_#{column}?".to_sym {
+          refresh_attachments(column_parse.call(send(column)), column)
         }
       end
 
-      def media_url_columns *columns
-        columns.each { |column| media_url_column(column) }
-      end
-
       def rich_text_column column
         media_url_column column, Proc.new { |val|
           Nokogiri::HTML(val).xpath('//img').map { |ele| ele.attr('src') }
         }
       end
+      
+      def media_url_columns *columns
+        columns.each { |column| media_url_column(column) }
+      end
 
       def rich_text_columns *columns
         columns.each { |column| rich_text_column(column) }