Raw implementation of commits stats page

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Refactor commits graph

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add tests for commits graph

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'refactor-graphs' into 'master'

Improving graphs: add new commits graphs page

This MR adds new page to graphs sections with commits statistic

![Screenshot 2014-09-26 20.32.01](https://dev.gitlab.org/uploads/dzaporozhets/gitlabhq/61fd84c4d6/Screenshot_2014-09-26_20.32.01.png)

See merge request !1124