Switch to Unicorn

Heroku now recommends unicorn as the default app server.

https://blog.heroku.com/archives/2013/3/13/running_rails_on_heroku_update

https://blog.heroku.com/archives/2013/2/27/unicorn_rails

Be sure to set a small backlog: http://devblog.thinkthroughmath.com/blog/2013/02/27/managing-request-queuing-with-rails-on-heroku/