fix registration and termination date to flip between empty-value and…

… 0000-00-00, thx to dxd

Signed-off-by: Michael Kaufmann <[email protected]>

lib/Froxlor/Api/Commands/Domains.php

@@ -292,7 +292,7 @@ public function add()
 					'0',
 					''
 				), true);
-				if ($registration_date == '0000-00-00') {
+				if ($registration_date == '0000-00-00' || empty($registration_date)) {
 					$registration_date = null;
 				}
 
@@ -301,7 +301,7 @@ public function add()
 					'0',
 					''
 				), true);
-				if ($termination_date == '0000-00-00') {
+				if ($termination_date == '0000-00-00' || empty($termination_date)) {
 					$termination_date = null;
 				}
 
@@ -929,15 +929,15 @@ public function update()
 				'0',
 				''
 			), true);
-			if ($registration_date == '0000-00-00') {
+			if ($registration_date == '0000-00-00' || empty($registration_date)) {
 				$registration_date = null;
 			}
 			$termination_date = \Froxlor\Validate\Validate::validate($termination_date, 'termination_date', '/^(19|20)\d\d[-](0[1-9]|1[012])[-](0[1-9]|[12][0-9]|3[01])$/', '', array(
 				'0000-00-00',
 				'0',
 				''
 			), true);
-			if ($termination_date == '0000-00-00') {
+			if ($termination_date == '0000-00-00' || empty($termination_date)) {
 				$termination_date = null;
 			}