Merge request commits view

Changes the commits view of a merge request to use the same layout as used in the project commits view.

As noticed from #923.

This also changes the commits icon on the tab to be fa-history, the same as used in the sidebar

Screenshots [Before](https://gitlab.com/uploads/stephanvl/gitlab-ce/8785737424/Screenshot_from_2014-12-29_20_39_25.png) - [After](https://gitlab.com/uploads/stephanvl/gitlab-ce/a3bf2a790f/Screenshot_from_2014-12-29_20_40_23.png)

See merge request !271