Build react-tools package on build, upload to builds site
Remove React from react-tools package

All of this is provided by the react package now, so there's no point in having
it available in multiple places. We *may* go back on that in the future for
shipping test utils, but for the time being, this is better for all.
Merge pull request #1040 from zpao/react-tools-revamp

react-tools revamp