Merge pull request #1 from evantahler/master

Catch up
Add app.json for Heroku button
Use PORT environment variable and default to 8080
- Add deploy button to README
- Correct capitalization
Clarify deploy button
Ensure app.json mirrors package.json
Merge pull request #482 from benburwell/master

Add a "Deploy to Heroku" button in the README file
Merge branch 'master' into lint