Users receive confirmation emails with unhashed link

https://trello.com/c/23nall7D/7-as-a-user-i-can-confirm-my-pickup-via-email

![userconfirm](https://cloud.githubusercontent.com/assets/8646429/5132595/17e33610-70cc-11e4-8029-575931f79a84.gif)

Shouldn't need all (any) of this. In your mailer template you can use view helpers, and they will automatically use the URL you've configured in `config/environments/*` (dev, production, etc). So this would be `availability_pickup_path(@availability, @pickup)`.