BUG: Hide initialization info when running Slicer as python interpreter.

Add method "qSlicerCoreCommandOptions::verbos" currently returning false
only  if slicer runs a python script directly passed as a command line
argument.

Later on, the system could be extended so that all initialization
information are hidden by default. They would be displayed
only if --verbose is explicitly passed.

Fixes #3285

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22345 3bd1e089-480b-0410-8dfb-8563597acbee