Hide end of commit message if it's too long

Before:
![screen shot 2014-07-08 at 4 03 03 pm](https://cloud.githubusercontent.com/assets/964084/3508169/3fb8888e-0687-11e4-8d9f-9f455f7f9ac7.png)

After:
![screen shot 2014-07-08 at 4 02 57 pm](https://cloud.githubusercontent.com/assets/964084/3508173/45cb709c-0687-11e4-80c4-fb0ec8a056d9.png)