Traitlets

It would be nice to add traitlets support but we are currently unable to do so because of the limitations around the asynchronous network requests and our current `CellWatcher` class implementation. Our current solution first returns a `Future` before that future is updated with the result. This presents a problem because traitlets expect the specified return type so when the Future is initially returned an error is raised.

If an improved solution for fetching async network requests can be found in the future it would be great to add traitlets support back in.