fixed bug, where a services has not been disabled when the URL has been emptied

src/Settings.php

@@ -71,6 +71,11 @@ class Settings {
 		//       submitted. The filter is called
 		//       "wpsi_save_services"
 		$value = json_decode(html_entity_decode(stripslashes($_POST["services"])));
+		// here we delete empty entries, because they should be deactivated
+		foreach ($value as $key => $url) {
+			if ($url === "")
+				unset($value->$key);
+		}
 		$services = json_encode(apply_filters("wpsi_save_services", $value));
 
 		update_option(Plugin::OPTIONS_KEY, $services);