Don't delegate connection to self (#436)

lib/acts_as_list/active_record/acts/position_column_method_definer.rb

@@ -72,17 +72,18 @@ def self.define_instance_methods(caller_class, position_column)
         cached_quoted_now = quoted_current_time_from_proper_timezone
 
         timestamp_attributes_for_update_in_model.map do |attr|
-          ", #{connection.quote_column_name(attr)} = #{cached_quoted_now}"
+          ", #{self.class.connection.quote_column_name(attr)} = #{cached_quoted_now}"
         end.join
       end
 
       private
 
-      delegate :connection, to: self
-
       def quoted_current_time_from_proper_timezone
-        connection.quote(connection.quoted_date(
-          current_time_from_proper_timezone))
+        self.class.connection.quote(
+          self.class.connection.quoted_date(
+            current_time_from_proper_timezone
+          )
+        )
       end
     end
   end