Alterar data para portugues

Tenho um plugin de calendário e estou tentando alterar a exibição da data para português, já tenho configurado no meu wp em configurações gerais o local e a hora atual, mas o plugin insisti em exibir o mês, dia em inglês.

Esse é codigo da parte de data do plugin, alguém sabe alguma opção que eu possa alterar para exibir a data em portugues?

protected function init()
  {
    // Stop the execution if we already executed the init function.
    if ($this->init)
      return;
    else
      $this->init = true;

    // Set the current time.
    if (!$this->current_time)
      // For non-WP scripts use: $this->current_time = time();
      $this->current_time = current_time('timestamp');

    // Current time -> current day of the week.
    $this->current_day_of_the_week = date('l', $this->current_time);

    // If the selected time is not set, then set it to the same value as the current time.
    if (!$this->selected_time)
      $this->selected_time = $this->current_time;

    // Selected time -> current day of the week.
    list($this->selected_day_of_the_week, $this->selected_month) = explode( ' ', date('l n', $this->selected_time) );

    // Selected time -> month and year.
    $date = date('F Y', $this->selected_time);
    list($this->selected_month_name, $this->selected_year) = explode(' ', $date);

    // Selected time -> first day of the month.
    $this->selected_first_day = strtotime('1 ' . $date);

    // Set the calendar start time.
    if ( date('l', $this->selected_first_day) != self::$days_of_the_week[$this->selected_first_day_of_the_week] )
      $this->selected_start_time = strtotime('last ' .  self::$days_of_the_week[$this->selected_first_day_of_the_week], $this->selected_first_day);
    else
      $this->selected_start_time = $this->selected_first_day;

    // Selected time -> last day of the week.
    $i = $this->selected_first_day_of_the_week + 6;
    $i = $i > 7 ? $i - 7 : $i;

    // Selected time -> last day of the month.
    $this->selected_last_day = strtotime( date('t ', $this->selected_first_day) . $date );

    // Set the calendar end time.
    if ( date('l', $this->selected_last_day) != self::$days_of_the_week[$i] )
      $this->selected_end_time = strtotime( 'next ' . self::$days_of_the_week[$i], $this->selected_last_day );
    else
      $this->selected_end_time = $this->selected_last_day;

    $this->selected_end_time = strtotime('tomorrow - 1 second', $this->selected_end_time);
  }