Clean up routes from starter index.js

[jenni]

1. Move routes into a routes folder for the sake of project's structure:

• Changed res.sendFile(__dirname + '/index.html') for res.sendFile('/index.html', { root: '.' }) to point to project root.
• Changed relative paths to load files, const {hashPassword, checkPassword} = require('./bcrypt') for const {hashPassword, checkPassword} = require('../bcrypt'), and so on so on.
• Added require('./routes/appRoutes')(app) in index.js to load routes.

2. Add .editorconfig for code style consistency along the project.

The king is dead, long live the q u e e r!