Merge pull request #12 from ConvertKit/update-mock-invoice

update mock_invoice for application_fee_amount

Author: christinalcole

lib/stripe_mock/data.rb

@@ -407,7 +407,7 @@ def self.mock_invoice(lines, params={})
         customer: "test_customer",
         object: 'invoice',
         attempted: false,
-        application_fee: nil,
+        application_fee_amount: nil,
         closed: false,
         description: nil,
         forgiven: false,