New method to find if discount is possible to be applied

src/main/java/de/rwth/swc/sqa/api/CustomerController.java

@@ -25,8 +25,6 @@ import io.swagger.annotations.ApiParam;
 @RequestMapping("/customers")
 public class CustomerController implements CustomersApi{
 
-
-
     @PostMapping("")
     public ResponseEntity<Customer> addCustomer(@ApiParam(value = "Customer object that should be added",required = true) @Valid @RequestBody Customer body) {
     	//id and birthday should not be empty