81: Add Notification component

[Caleb-Ellis]

Done

• Added Notification
• Includes Default, Information, Positive, Caution and Negative types
• Added classnames to dependencies
• Added stories/knobs to Storybook
• Added snapshot tests
• Updated Storybook name in upper-left corner to 'Vanilla Framework React' to be a bit clearer

QA

• Pull code
• Run yarn lint and yarn test to ensure there are no linting or testing errors
• Run ./run serve --watch and navigate to http://localhost:8102/
• Verify the Notification component in Storybook matches the Vanilla docs

Fixes

Fixes #81

[webteam-app]

Starting demo at: http://vanilla-framework-react-pr-96.run.demo.haus/

[Caleb-Ellis]

@anthonydillon I've now made children a requirement and replaced the if statements with a switch case

[webteam-app]

Starting demo at: http://vanilla-framework-react-pr-96.run.demo.haus/