No more devDependencies

Since 2018, Create React App has put its react-scripts in normal dependencies. This frees us from the awkward force-install of devDependencies to run the build.

Heroku auto-build & React hooks

• switch to Node.js buildpack's auto-build
• migrate to React hooks

create-react-app 2.1.2

Upgrade to react-scripts 2.1.2 & react-dom 16.4.2.

create-react-app 2.1.1

• Upgrade to Create React App 2.x
  • Replace react-ui/ with the upgrade
  • Re-implement example API calls
• Upgrade to Node 10.x
  • Improve & clarify development mode