New Amazon S3 region - Stockholm

[fredvik]

Please add support for the recentely opened S3 region EU (tockholm).

I can confirm that it works to add the following to to class-destination-s3.php:

array(
                'label' => __( 'Amazon S3: EU Custom (Stockholm)', 'backwpup' ),
                'value' => 'eu-north-1',
            ),

[danielhuesken]

We will add it