Make the app a well-behaved PWA

AC:

1. `<title>` element in `index.html` is updated to match the app name (i.e. “What’s near me?”)
2. Update `public/manifest.json` with the app `name` and `short_name`
3. Update `public/favicon.ico`, `public/logo192.png`, and `public/logo512.png` with something other than the default React icon