Ledger test

https://ripplelabs.atlassian.net/browse/RIPD-432

@JoelKatz @vinniefalco 

This is still somewhat of a WIP, but it is time to get the bulk of it onto develop, get some experience with it, and see where we go from there.
Management wants this project done, and this falls under the heading of feature creep.  Happy to work on this under an additional RIPD.