Fix bug about updated property for Phalcon\Session\*

```php
$session = new \Phalcon\Session\Adapter\Files();
var_dump($session);
$session->start();
var_dump($session);
```
```output
object(Phalcon\Session\Adapter\Files)#57 (3) {
  ["_uniqueId":protected]=>
  NULL
  ["_started":protected]=>
  bool(false)
  ["_options":protected]=>
  NULL
}
object(Phalcon\Session\Adapter\Files)#57 (3) {
  ["_uniqueId":protected]=>
  NULL
  ["_started":protected]=>
  bool(false)
  ["_options":protected]=>
  NULL
}
```