Update / replace React-intl in the future

[kuijoe]

The react-intl internalization plugin for React is going to break the site when updating the current version 2.9.0 to 3.x. Some of the methods we are currently using were renamed and or removed in the new version. The current version of react-intl is using deprecated lifecycle methods such as componentWillMount so it should be updated or even replaced in the near future.

https://github.com/formatjs/react-intl/blob/master/docs/Upgrade-Guide.md

An alternative internalization library could be https://react.i18next.com/