QtIFW

Add the possibility to have an settings button int the ui.

Added some more code to be able to properly relayout the
buttons after show/ hide of the settings button. We always
need to call this now since QWizard won't take care of our
own passed buttons.

Change-Id: I8dc957ba43b79239164ab1e9032ffbd86b095501
Reviewed-by: Niels Weber <niels.2.weber@nokia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>