Show changed file list from git commit dialog

With fastSHA, it it fast enough to show chagne list.

- changed file # > 5, then show scroll.

@dinhviethoa

![image](https://f.cloud.github.com/assets/756988/2528235/681fa1d4-b50d-11e3-86f4-7c3173f2818d.png)

![image](https://f.cloud.github.com/assets/756988/2528157/b6e88908-b50c-11e3-96cd-08067452ed25.png)