Remove purescript-react-dom

[dwhitney]

Hey this looks like a cool project! One thing I've noticed on most purescript projects like this is they include purescript-react-dom as a dependency. Doing this means the library will not work with React Native in any capacity -- any direct reference to the DOM will cause the app to crash. Since there is only one file (Refract.purs) that uses purescript-react-dom, I wonder if you wouldn't make a purescript-refract-dom library that contained the code you need. That would enable this library to be used with React Native -- Just a thought