QtIFW

Make sure we remove ui elements we added.

This fixes several problems, e.g. once a component script has been
run, possible ui elements or even complete pages have been added.
On a second component script run these elements would have been
added again etc... Now we remove all pages and widget by default.

Change-Id: I47a3283ce06767c28529201432b71c0b4f12e533
Reviewed-by: Niels Weber <niels.2.weber@nokia.com>
Reviewed-by: Alexander Lenhardt <alexander.lenhardt@nokia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>