Refactor to allow passing filtering/limiting args to each method

Given the long goal of filtering/limiting across states, remove
state as a required argument to the constructor and accept
filtering arguments to the different methods, imagining an
eventual chainable interface that breaks out filtering, limiting
and writing as separate calls.

I don't know if this is the best way to do it, but it makes the
most sense to me today.

Addresses #39
First pass at bakery

There's still a lot to do, but at this point it:

* Grabs and flattens data
* Writes CSV and JSON

Addresses #39