Fix for default voucher value could be out of range

https://github.com/opencart/opencart/pull/1086

https://github.com/opencart/opencart/commit/4a520f67f0a187626364d4e2350852e2829cd4bd
Closes #59 Apostrophe in Customer Group name fix

https://github.com/opencart/opencart/commit/3358f95638abbe3a4d1e504dc3486a3249a3a5fb