Bring babel presets up-to-date
Bring babel presets up-to-date

* Use `babel-preset-latest` to stay current with the latest approved ES
standard.
* Use `babel-preset-stage-1` instead of `babel-preset-stage-0` to back
away a bit from the bleeding edge.  We weren’t using anything from
stage-0, but we do want the export-extensions from stage-1

CodingZeal/react-boilerplate,CodingZeal/react-boilerplate