Merge pull request #465 from e-piksel/master

Added config_review_mail in opencart.sql
fix for

Notice: Undefined variable: product_data in /home/mydomain/public_html/store/catalog/model/checkout/coupon.php on line 85
Merge branch 'master' of https://github.com/opencart/opencart
started adding my own version of vqmod.
Added allow guest review enable/disable