React/Web-Based Setup Wizard & Configuration Framework

[kevinschaich]

Closes #18

To Do:

• [x] Add React to project
• [x] Index/welcome page
• [x] Redirect to onboarding wizard or settings page depending if user has set everything up
• [x] Update other configuration parameters like CATEGORY_OVERRIDES
• [x] Migration script for current config format
• [x] Plaid Onboarding
• [x] Sheets Onboarding
• [x] Get existing configured tokens
• [x] Test existing tokens
• [x] Configure new token
• [x] Add formatter/linter to project
• [x] Update token
• [x] Remove token
• [x] README updates & polish
• [x] All possible default parameters updated
• [x] Update index.js & CI connections
• [x] End to end test of onboarding flow
• [ ] ~Pluggable Onboarding~

[kevinschaich]

Done! 🎉