Users can use link to confirm their pickup

https://trello.com/c/QdJFf7qp/12-as-a-user-i-can-confirm-my-pickup-using-a-button

![userconfirm](https://cloud.githubusercontent.com/assets/8646429/5114923/0f9221d6-700b-11e4-9120-5946efbeb8f8.gif)

Done on purpose -- this was just to test the functionality of the confirmation link. Eventually this will be done via email. As per security, I'm going on the assumption that the email given is owned by the person who made the pickup.