QtIFW

Remove fetch and implement "lazy" fetch.

Now it feels better then to bring up the dialog and start
the fetch instantly, the user now has the opportunity to edit
the network settings first and on "Next" we fetch the tree.

Change-Id: I1ebce333bf5157421f2b62afbe5630b0ec1e0134
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>