[RFC] Split OrderInterface (one from CoreBundle) into several

The interface already quite big. What if we split it a bit:

```php
<?php

interface OrderInterface extends FooInterface, BarInterface, BazInterface
{
}
```

For example get\set payment method could be moved to separate interface, which could be placed to payments bundle. Shipping method to shipping bundle and so on.

This way for example payum actions could be decoupled from core bundle and require `OrderBundle` and `PaymentsBundle` bundles only. It allows one reuse these actions with orders developed in house without downloading half of the sylius.

Thoughts?