Small tweaks to attributions max-width

Before
![capture d ecran 2014-08-26 a 15 31 03](https://cloud.githubusercontent.com/assets/21686/4044981/5b148762-2d25-11e4-9e87-1e1f2077219c.png)

After
![capture d ecran 2014-08-26 a 15 31 23](https://cloud.githubusercontent.com/assets/21686/4044979/5b0b81bc-2d25-11e4-87fd-dde16dd09b1b.png)

ping @elemoine