Add user-links & tweak alignment

Theoretically this will work on the crate pages, but I haven't been able to test it.

Old:

![cratesio-old](https://cloud.githubusercontent.com/assets/1203825/5153152/e417b282-726c-11e4-85d8-5e5933bed79d.png)

New:

![cratesio-new](https://cloud.githubusercontent.com/assets/1203825/5153154/f02545c6-726c-11e4-9937-332600b305b4.png)