Set up basic app architecture at the App.js level in order to improve developer experience, especially for first time Tailwind users.

[jamesncox]

Before any components or subsequent styles are implemented, it makes sense to lay some basic groundwork at the App.js level.

This is a subtask of #14

TO DO

• Rip out the vanilla CSS class in App.js
• Add Tailwind utitlity classes to implement styles and structures that will be inherited by the rest of our pages and components.