Option to remove signs from generated diff

With signs:
![screen shot 2013-05-21 at 5 11 55 pm](https://f.cloud.github.com/assets/4164/545164/49ee341e-c25b-11e2-8fa7-0327179844d4.png)

Without signs:
![screen shot 2013-05-21 at 5 02 45 pm](https://f.cloud.github.com/assets/4164/545165/4dd20f7e-c25b-11e2-878f-d3b7210349c2.png)