Fix python log API, cat and message are now need

Change-Id: I28cf77002080d8975f1a4734e6d0304fd1933f11
Reviewed-on: http://gerrit.aldebaran.lan/44734
Reviewed-by: cgestes <gestes@aldebaran-robotics.com>
Tested-by: hcuche <hcuche@aldebaran-robotics.com>