QtIFW

Simplify logging

Let VerboseWriter solely handle logging to the destination file.
qt_message_handler takes the role of logging to cout. This allows
us to get rid of the twisted stream logic in utils.cpp, and
furthermore let us get rid of the buggy debugstream.

Change-Id: I5cf2e41b126a90025825a0d93f95b41d783ef22a
Task-number: QTIFW-524
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>
Reviewed-by: Niels Weber <niels.weber@digia.com>