Let the logger merge in the formatting arguments, so that logs can be grouped.

The reason why you want to let the logger pass the string formatting arguments is so logging can be grouped properly. Otherwise this happens:

![screen shot 2013-08-12 at 4 32 36 am](https://f.cloud.github.com/assets/48965/944613/1c97f090-02c5-11e3-9d37-d1d3e8477f2e.png)