Users can sign in as admins

https://trello.com/c/XdI8bkp1/1-as-an-admin-i-can-log-in-using-my-credentials

![image](https://cloud.githubusercontent.com/assets/8646429/5074881/be71cacc-6e5c-11e4-9f6b-6d2de6232ffd.png)