Do not suggest PackStation as service point

[robinero]

Related to #64.

Prerequisites:

• ServicePoints enabled

When a customer enters their shipping address, a PackStation can be automatically selected as the shipping destination. However, it's not always clear whether the suggested PackStation requires a post number, which can cause issues for the shipping party.

The following code is responsible for selecting the closest service point:

plugin-magento2-release/Model/Service/ServicePoint.php

Lines 59 to 73 in d929411

	public function getClosest($postalcode, $country)
	{
	$servicePoints = $this->search($postalcode, $country, 13);
	if (!is_array($servicePoints)) {
	return false;
	}
	foreach ($servicePoints as $servicePoint) {
	if ($servicePoint->shopType !== 'packStation' || $servicePoint->country !== 'DE') {
	return $servicePoint;
	}
	}
	return false;
	}

Wouldn't it be better to either exclude all PackStations or modify the if statement to verify whether the shipping address country is in a list of allowed PackStation countries that don't require a post number?