Differentiates between production and sandbox receipt verification base URL string.
Differentiates between production and sandbox receipt verification base URL string.

Mark sandbox receipt verification base URL string as unused for now.

songsinh88/CargoBay,mattt/CargoBay,hanhailong/CargoBay,dxd214/CargoBay,ycaihua/CargoBay,vvw/CargoBay,LiuDeng/CargoBay