Improve DSL for notifications

[abitdodgy]

This is really minor but it makes sense. When processing a notification, you need to call @notification.id to pull up the reference number (order number you provided).

I think it readers better if it were @notification.order_id or @notification.reference_id to stay consistent with PagSeguro's API. Check this out:

class PagSeguroNotification
  def initialize(notification_code)
    @notification = PagSeguro::Notification.new(PAGSEGURO_EMAIL, PAGSEGURO_TOKEN, notification_code)
  end

  def get
    # I'm grabbing the order by calling @notification.id, which can be confusing
    # Calling @payment.id doesn't read better either 
    order = Order.find(@payment.id)
    # ...
  end
end

[teonimesic]

I guess we could create an alias to id as reference (and not reference_id, since reference is the actual attr name that pagseguro returns). I dont like order_id, because users may not name it Order. It could be Invoice, Payment or something else completely.

But i dont intend to remove id, i really think that it makes sense for a notification's id to return the reference, since it is supposed to be a unique payment identifier on the system. It also is very well documented, both on specs and README.

[teonimesic]

I added a reference method to both payment and notifications. So you can now do something like:

PagSeguro::Payment.new email, token, reference: "some id reference"
notification.reference # => "some id reference"