profile page: icon and hover explanation for auths

![screen shot 2014-10-16 at 11 07 00](https://cloud.githubusercontent.com/assets/464192/4660066/df75e788-5513-11e4-9b50-85cc0be3afc5.png)



I would say: `You can sign in with` or `Available sign in options`

I'm using sign in everywhere instead of login and the rest of the titles don't have `:`.