Switched orderbook to show depth and not totalValue

Here is what it looks like:

![screen shot 2014-10-06 at 5 52 19 pm](https://cloud.githubusercontent.com/assets/5728307/4535863/3901fd96-4dbc-11e4-9f4d-fc70cdf7051a.png)

Implements #911
You never use the result of ```map```. You normally want ```forEach``` if you are not actually transforming the values, but in this case you should actually use ```reduce```. ```reduce``` performs an operation on a set of values to produce a single value.

https://lodash.com/docs#reduce