Some times need to add custom classes in wordpress tinymce editor. This is simple solution to do this:

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add_filter('tiny_mce_before_init', 'oi_tinymce');
function oi_tinymce($settings) {
    $new_styles = array(
        array(
            'title' => 'None',
            'value' => ''
        ),
        array(
            'title' => 'Table',
            'value' => 'table',
        ),
    );
    $settings['table_class_list'] = json_encode( $new_styles );
    return $settings;
}