Do not create an "invalid" key when Org elements are empty. (#325)

This has been present since the initial commit. However it seems nothing
handles 'invalid' keys after that or does anything with it. It's unclear
what the meaning was or at least is. It does produce these keys in parsing
metadata in SimpleSAML without (some) org elements.

Author: thijskh

src/SAML2/XML/md/Organization.php

@@ -63,23 +63,14 @@ public function __construct(DOMElement $xml = null)
         $this->Extensions = Extensions::getList($xml);
 
         $this->OrganizationName = Utils::extractLocalizedStrings($xml, Constants::NS_MD, 'OrganizationName');
-        if (empty($this->OrganizationName)) {
-            $this->OrganizationName = ['invalid' => ''];
-        }
 
         $this->OrganizationDisplayName = Utils::extractLocalizedStrings(
             $xml,
             Constants::NS_MD,
             'OrganizationDisplayName'
         );
-        if (empty($this->OrganizationDisplayName)) {
-            $this->OrganizationDisplayName = ['invalid' => ''];
-        }
 
         $this->OrganizationURL = Utils::extractLocalizedStrings($xml, Constants::NS_MD, 'OrganizationURL');
-        if (empty($this->OrganizationURL)) {
-            $this->OrganizationURL = ['invalid' => ''];
-        }
     }