Maintenance upgrades

[that1matt]

• Upgrade React to 16.3.3
• Upgrade to Babel 7
• Upgrade eslint, eslint-plugin-babel, babel-eslint, hoist-non-react-statics, types deps
• Add experimentalDecorators to tsconfig.json
• Upgrade eslint config
• Run eslint auto fix
• Change prepublish to prepare for npm scripts
• Add raf & caf polyfill for tests
• Change Readme to reflect fork