Update to react 15 (and all the other packages)

[gavmck]

Hey there,

I was trying to use this plugin on a react 15.4.2 app and having difficulties with the call to findDOMNode. In the process of updating, it led me down a rabbithole where everything needed updating/tweaking.

Should be all good to go now and have switched findDOMNode to use ref function instead.

Should fix #20

[zackify]

Looks good to me, one little thing though

The ref attribute takes a callback function, and the callback will be executed immediately after the component is mounted or unmounted.

Is this before componentDidMount is called? I'm assuming so, which means everything would work perfect. Good job

[gavmck]

Yep, should only be called after we know what's in render.

Initialization that requires DOM nodes should go here. 

https://facebook.github.io/react/docs/react-component.html#componentdidmount

[gavmck]

Oh there's a more relevant example in the docs here: https://facebook.github.io/react/docs/refs-and-the-dom.html#adding-a-ref-to-a-class-component

[dphaener]

@gavmck This looks good! Thanks for working on this. I'm going to go ahead and merge and just do a few smoke tests locally, and if everything looks good I'll release shortly thereafter.