nurse shark, first draft

Open for feedback, but *not* for merge. I'll be working on this branch as well to update the viz code for the new data model.

The only things you can test here presently are validation with the node script `dev/validate-with-timing.js` and the tests for nurse shark, `test/nurseshark_test.js`. The visualization itself is broken, as expected.

@cheddar I added a couple of things that were missing to the schematron, as per my comment on the Trello card.
Hrm, I'd be a +1 on getting it out of the repo sooner rather than later.  Another option if setting up a new repo and npm and all that is too much is to just create an s3 bucket that you can push things up to.  You can put like a date string in each of the things uploaded or something to version them from each other, or whatever.

If you want to do that, let me know and I can set you up the s3 bucket.