Prepare 4.0.0 alpha release
Prepare 4.0.0 alpha release

facebookincubator/create-react-app,facebookincubator/create-react-app,jdcrensh/create-react-app,jdcrensh/create-react-app,jdcrensh/create-react-app,facebookincubator/create-react-app,jdcrensh/create-react-app