QtIFW

Add a logging category and debug for http download

Sometimes installing fails due to a problem in server.
Since downloading can happen from mirror, it is hard to
detect where the problem is. Print the IP address where
the download actually happens to ease the problem solving.

Change-Id: I31e15c2b1926745c251093cd1663d1ca1c65bff6
Task-number: QTIFW-813
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>