api fixes

According to [RFC2616](https://www.rfc-editor.org/rfc/rfc2616#section-10.2), APIs should return 2xx status codes if the request was correct.
The response should be status 200 with an empty result array.

htdocs/commande/class/api_orders.class.php

@@ -259,9 +259,7 @@ class Orders extends DolibarrApi
 		} else {
 			throw new RestException(503, 'Error when retrieve commande list : '.$this->db->lasterror());
 		}
-		if (!count($obj_ret)) {
-			throw new RestException(404, 'No order found');
-		}
+
 		return $obj_ret;
 	}