Add license.
Add timestamp to ms conversion to model

I may extract these later into a utility class. Right now the model
seems like the right place to bundle these, as that's one of the places
it'll be used.

It'd be fairly painless to extract this into it's own util module.

- Add unit tests
- add timestampToMillis method
  Uses a table look up because the conversion is fully uniform and
  extremely verbose.
- extract magic numbers into closure constants.