add batch and credit note on sales_return

new file on

db/patch/
- 20130918_sales_return_detail_batch

web/application/helpers/
- credit_note.php

alter file on
web/application/controllers/
- item_batch.php

web/application/helpers/
- recalculate.php
- sales_engine.php

web/application/retail/sales_return/
- html.php
- js.php