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.
Did we not decide to delete this code from here?  As I said, I think you should extract this as a separate test, and ensure that this commented-out code has exactly the same meaning as the code you're actually using.