QtQuickApp: Fix look of component set options page on Mac

Use window title, like it is done for the other wizard pages.

Change-Id: Ie02c41606a02eadf61548f28c5533d1495721077
Reviewed-on: http://codereview.qt.nokia.com/1782


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Alessandro Portale <alessandro.portale@nokia.com>