code: function pushTask(client, task) {
    /*jshint validthis: true */
    if (!this.tasks[client]) {
      this.tasks[client] = [];
    }
    this.tasks[client].push(task);
  }
docs: Pushes task for client.
  @param {string} client Client identificator
  @param {object} task Task information
  @param {string} task.task_name Damson task name
  @param {object} task.options Damson task arguments
  @param {string} task.driver_name Damson driver name