AthenaMonitoring: Enable flake8 and make python code compliant

Control/AthenaMonitoring/CMakeLists.txt

@@ -75,6 +75,7 @@ atlas_add_component(
 )
 
 # Install files from the package:
-atlas_install_python_modules( python/*.py )
+atlas_install_python_modules( python/*.py 
+                              POST_BUILD_CMD ${ATLAS_FLAKE8} )
 atlas_install_joboptions( share/*.py )
 atlas_install_scripts( share/Run3DQTestingDriver.py )
\ No newline at end of file

Control/AthenaMonitoring/python/AtlasReadyFilterTool.py

+# Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+
 # Set up the ATLAS Ready filter tool
 def GetAtlasReadyFilterTool():
    from AthenaCommon.Logging import logging

Control/AthenaMonitoring/python/FilledBunchFilterTool.py

+# Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+
 # Set up the filled bunch filter tool
 def GetFilledBunchFilterTool():
    from AthenaCommon.Logging import logging

Control/AthenaMonitoring/python/GenericMonitoringTool.py

-from AthenaMonitoringKernel.GenericMonitoringTool import GenericMonitoringTool,defineHistogram
\ No newline at end of file
+# Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+from AthenaMonitoringKernel.GenericMonitoringTool import GenericMonitoringTool,defineHistogram  # noqa: F401