STYLE: Relocate logging initialization from slicer/init to slicerqt.py

Relocate configuration of the application loggers into the application
initialization script. This is done anticipating the possible introduction
of lazy loading of slicer module attributes.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25124 3bd1e089-480b-0410-8dfb-8563597acbee