QtIFW

Fix annoying warning that the file can not be deleted.

Define the downloadable target inside the remote directory
it belongs to, avoids the unnecessary delete inside the task
destructor. The temporary dir deleter will take care of it.
Change-Id: I4858a71dc714a33f1afb00eb2b2a167294899461
Reviewed-by: Niels Weber <niels.weber@digia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>