Added trytond-gift-card as a dependency #6000


![gc_1](https://cloud.githubusercontent.com/assets/3972835/5000078/2b51cad2-6a0e-11e4-9401-2f9bea201816.png)

![gc_2](https://cloud.githubusercontent.com/assets/3972835/4999261/ca42c25c-6a06-11e4-98de-6f19560178a9.png)

```python
def __init__(self, product_id, *args, **kwargs):
    super(GiftCardForm, self).__init__(*args, **kwargs)
    self.product, = Product(product_id)
    assert self.product.template.is_gift_card, 'Expected Gift Card, Got %s' % self.product.rec_name
```