Update success.php

If totals are not unset on success, store credit can be double spent using the multiple browser method and cause negative store credit balance. 
I cannot think of any reaon why totals should not be unset on order success, so I have added one line for doing so.
Merge pull request #1101 from kabatza/patch-1

Update success.php
fix for add this issue. also some backend work done
Merge branch 'master' of https://github.com/opencart/opencart
massive update to the admin template
Merge branch 'master' into development-feature-profiles

Conflicts:
	upload/admin/view/template/catalog/product_form.tpl
	upload/admin/view/template/sale/order_info.tpl