Use React 15 for the website (client-side)
Use React 15 for the website (client-side)

Summary:It doesn't use v15 for the server-side generation. That requires changes to react-page-middleware and I just wanted to get this up quickly.

Fixes #323
Closes https://github.com/facebook/draft-js/pull/330

Differential Revision: D3210313

fb-gh-sync-id: 29779759cc0a14802144c0ee84d69f07a4a14dff
fbshipit-source-id: 29779759cc0a14802144c0ee84d69f07a4a14dff

tonygentilcore/draft-js,dirkholsopple/draft-js,dirkholsopple/draft-js,davidchang/draft-js,TripleDip/draft-js,SciMts/draft-js,TripleDip/draft-js,SciMts/draft-js,johnmpotter/draft-js,davidchang/draft-js,facebook/draft-js,johnmpotter/draft-js,tonygentilcore/draft-js