suppress error messages for qfind

I really like qfind, but found the grep messages that foo is a directory to just take up a lot of space, especially when traversing git folders. Added the -s to suppress these messages. 
![2013-08-21-205559_1920x1080_scrot](https://f.cloud.github.com/assets/1045990/1005764/e608744c-0ac5-11e3-8974-f070161dfc85.png)