FolderListModel: Fix setting of directory in componentComplete().

Discovered when fixing

Task-number: QTBUG-32139

Change-Id: I94d1a958069666ed43db146a7393e5f1ff4e177e
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
FolderListModel: Do not return invalid URLs like "file:" when navigating up.

Task-number: QTBUG-32139

Change-Id: I715b97eb85bc4235de6a2bb696131efae56477fd
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>