Merge pull request #1095 from eka7a/master

Selected default customer group when adding a new tax rate
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
Added product images ORDER BY sort_order on admin page