Stop using react-notify

[ckingbailey]

The original project our form comes from uses ReactNotify. This library is unmaintained, and was never good in the first place.

Let's get ReactNotify out of this project.

There are already a couple of methods on the store to handle adding and removing notifications. That part we can keep. For notice UI we could either roll our own modal, or find another library to use. I like the idea of rolling our own because (1) it would be pretty simple, and (2) we could have a system of inheritance or HOC where a Notifier class can display a top banner, a modal of any size, or any other kind of notice UI we might want to show. If there exists an easy-to-use, flexible, well-maintained library for this, then that would be fine, too.