Identity - Profile Activity - GuardianWitness Contributions

![screenshot from 2014-07-07 16 07 05](https://cloud.githubusercontent.com/assets/383630/3497080/75f49252-05e8-11e4-9bce-25dba10f1104.png)

It would be great if these timestamps were also clickable. On Twitter and in Discussion they are, so that would make sense.