code: function wait(id, callback) {
  		var promises = [];
  
  		self.transactions[id] = {};
  		lib.each(self.workers, function (worker) {
  			var deferred = Q.defer();
  			self.transactions[id][worker.id] = deferred;
  			promises.push(deferred.promise);
  		});
  
  		Q.spread(promises, callback);
  	}
docs: Create a transaction which resolves when a response
  is heard from each active worker