ReactTools is deprecated, it doesn't belong at the root of the project. We'll remove it after 0.14 but for now this moves it so that it's contained and not intermixed with the rest of the project. The currect behavior of copying src/ into the package is maintained.
This reworks a few things in building and distributing React. The biggest change is using fbjs to share dependencies with other libraries. We're also using Gulp for some build steps.
