Created by: wdhorton
Fixes #473 (closed). I thought the best approach would be calling npm view react[-dom] version and then using the output. If it fails, it falls back to the old method of getting the version. The other alternative I considered was just doing a separate install of react and react-dom, but then you'd end up with more extra npm installs.
Test plan: I ran init and the new app had version ^15.3.1 in the package.json, instead of ^15.3.0, which is how it is in the create-react-app repo and when creating a new app off of master.