Assembles test results from the worker processes and outputs the results
to the console.
function CucumberReporter (eventMediator) {
  var options = {
    snippets  : true,
    stream    : process.stdout,
    useColors : true
  };
  this.failureCount  = 0;
  this.eventMediator = eventMediator;
  this.formatter     = DotFormatter(options);

  // all feature files are finished
  this.eventMediator.on('end', this.allFeaturesDone.bind(this));
}