Data analysis of the charge_state

I don't know if this is worth pulling into master (your call, Hans), but I'd love for you guys to try this on your data.
Just pull this branch, restart visualize and then go to localhost:8766/test
The graph for me looks roughly like this:
![distanceovercharge](https://f.cloud.github.com/assets/237471/1079822/ccf5c396-1552-11e3-866e-956e335b5cd3.png)
Which shows that there is something really weird with the correlation between reported SOC and reported rated_range. And that at least for my car the data I have does not correspond to what appears to be the 'accepted wisdom' of how rated range works.
I've posted a lengthy response with these data in the Energy Accounting thread. Please chime in with the data from your 85s - you may have to change the hardcoded slope / range used for the trendline in order for this to work for your data...
http://www.teslamotorsclub.com/showthread.php/18528-Energy-accounting/page6?p=431015&viewfull=1#post431015