Timeline improvements

More context for comments
* who is it assigned to
* link to comment
![screenshot from 2014-02-12 14 16 13](https://f.cloud.github.com/assets/810040/2148149/80089ba6-93df-11e3-99a5-55ef70f6eab6.png)

More context for commits
* see individual commits
* see diff for all commits 
![screenshot from 2014-02-12 14 17 18](https://f.cloud.github.com/assets/810040/2148154/a6dc82a6-93df-11e3-9de8-64c4a246f1b9.png)

Todo
- [ ] Issue labels
- [ ] Issue age
- [ ] Other ?