QtIFW

Introduce TaskItem and Authenticator role.

Make sure every reply can use its own authenticator and
pass back the initial task item to the caller(task tracking).

Change-Id: I8b57dbf9d70f3061a91e436a578ec7e0c3138beb
Reviewed-by: Niels Weber <niels.weber@digia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>