Determine best source for fiat historical data.

[jwaggs]

Description

Gathering historical data on a precise level that is better than daily stats would be cumbersome to build and maintain. Rather than doing this from scratch, I'm proposing we fork a repository that can back fill the data in our own database, and then keep it up to date moving forward.

A valid option for this is Zenbot. Back-filling data on a per exchange basis is a subset of their features.