"When I Get [on the Web]" or got ready for Heroku deployment

Changes are for making deployment to Heroku easily repeatable. Tenants of this:

- Versions of gems statically assigned. This makes the build repeatable since direct and transitive dependencies won't quietly change upon deployment, even if the Gemfile.lock is deleted (such as Heroku does). This means anyone deploying it will get the same as what we see.
- Instructions on deploying to Heroku
- App server: Unicorn is used for production, while WebBrick is used for development
- Some updates to production setup instructions. However, this is a work-in-progress as it doesn't describe how to setup Unicorn and/or Apache manually (like Heroku does for you).