Add React hooks

[compulim]

Description

Bumped to react@16.8.6 and added React Hooks.

Upgraded all React class components into functional components.

Changelog

Breaking changes

• We moved to React Hooks and it requires React 16.8.6 or up
  • Hooks will allow us to write simpler and more maintainable code
  • Developers can use our React Hooks to perform various operations

Changed

• Moved all code to React functional components, in PR #31
• *: bump dependencies, in PR #31
  • @babel/cli@^7.6.2
  • @babel/core@^7.6.2
  • @babel/plugin-proposal-object-rest-spread@^7.6.2
  • @babel/preset-env@^7.6.2
  • babel-jest@^24.9.0
  • jest@^24.9.0
  • react-dom@16.8.6
  • react@16.8.6

Added

• Added React Hooks, in PR #31
• Added ESLint and Prettier, in PR #31

Fixed

• Fix atStart was not reporting correctly, in PR #31