auto-login feature

![screenshot on 2013-10-30 at 15 10 05](https://f.cloud.github.com/assets/2024208/1435044/57ec0c5c-4132-11e3-956b-5beb40187958.png)

![screenshot on 2013-10-30 at 15 10 47](https://f.cloud.github.com/assets/2024208/1435048/6f40818a-4132-11e3-97cf-7832a2ef7099.png)

auto-login per site