Foreman » Smart Proxy

With the recent changes to Rack and Sinatra (https://github.com/sinatra/sinatra/commit/0f9a959253bdf0c39422ffb9b60278df46ef0248, https://github.com/rack/rack/blob/master/lib/rack/server.rb) we bind localhost for dev setups and 0.0.0.0 for production. Let's add a config entry so I can override this in my development setup.