package.json: update reactify and pin immutable version
package.json: update reactify and pin immutable version

We pin immutable to 3.0.x before [facebook/immutable-js#195][] is fixed.

[facebook/immutable-js#195]: https://github.com/facebook/immutable-js/issues/195

TribeMedia/react-forms,D1plo1d/react-forms,lrowe/react-forms