Need refactor

I think in 2020 this part of code need in refactor. There's composer's autoload already.

> namespace {
>     const DS = DIRECTORY_SEPARATOR;
>     require_once __DIR__ . DIRECTORY_SEPARATOR . "AbstractService.php";
>     require_once __DIR__ . DS . ".." . DS . "Helper" . DS . "Validation.php";
> }
> 

Currently it leads to 

> Notice: Constant DS already defined