Refactor namespaces

- Remove unused use statements
- Add required use statements
- Escape global classes

src/Model/Group.php

@@ -10,7 +10,6 @@ use Friendica\Core\L10n;
 use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
-use Friendica\Util\Security;
 
 /**
  * @brief functions for interacting with the group database table