Merge pull request simplesamlphp#71 from creativeprogramming/patch-1

The 'idpdisco.extDiscoveryStorage option lacks a default NULL value in discopower.

Author: jaimeperez

modules/discopower/lib/PowerIdPDisco.php

@@ -190,7 +190,7 @@ public function handleRequest() {
 		$idp = $this->getTargetIdp();
 		if($idp !== NULL) {
 
-			$extDiscoveryStorage = $this->config->getString('idpdisco.extDiscoveryStorage');
+			$extDiscoveryStorage = $this->config->getString('idpdisco.extDiscoveryStorage',NULL);
 			if ($extDiscoveryStorage !== NULL) {
 				$this->log('Choice made [' . $idp . '] (Forwarding to external discovery storage)');
 				SimpleSAML_Utilities::redirectTrustedURL($extDiscoveryStorage, array(