Use blog timezone settings when retrieving Stats

Fix #1220 
/cc @astralbodies 
This ends up displaying the day in `yyyy-MM-dd` format, which isn't very friendly and may be confusing depending on locale. How about using the same `MMM d` format that's used by the bar chart? 

![device-2014-08-21-103611](https://cloud.githubusercontent.com/assets/3903757/3997650/2efc36f8-2941-11e4-8af0-dd645291e6b7.png)