Rewrite chef_node handler with Ridley and api_request

Spice is deprecated and this handler was making a custom connection to the Sensu API, so I've replaced Spice with Ridley, and the custom HTTP request with `api_request`.  Ridley inside handler was doing something bizarre and not initializing the Celluloid thread pool correctly, so as a workaround I've put in a single retry after manually booting Celluloid.