@afeld => Don't delimit numbers less than 1 with commas

Hey there, enjoying your gem very much!

Had an issue with reporting statistics less than 1:
![screen shot 2014-05-05 at 11 29 00 am](https://cloud.githubusercontent.com/assets/4393191/2879474/610783c2-d46a-11e3-85d7-cfeea3b1d3d3.png)

This PR refrains from adding commas between every three digits for numbers less than 1. In a follow up PR, I'll change the precision of the input into `number_with_delimiter(number)`. Would you say 3 significant digits is a good place to round?