Change from Thin to Unicorn

As of three days ago Heroku started suggesting (Unicorn)[https://blog.heroku.com/archives/2013/3/13/running_rails_on_heroku_update] \(see #5 "Improving Cedar Supprt"\). The company I contract with has been supporting a client using Unicorn on Heroku for months now. You can handle a larger load with fewer Dynos therefore saving money and scaling better.

My change establishes Unicorn as the server and also adds Unicorn Worker Killer (an almost must have if you want to try three Unicorn Workers per Dyno rather than two).