v2.4.2

Tasks can now be tagged at registration time.

• The task registration methods accept an optional tags argument. When
  provided, the extra tags are merged into each task's own tags as it is
  registered — applied across register_task, register_from_module, and
  register_from_dict.
  (#102)
• Bumped python-json-logger to >= 4.1.0 and switched JSON logging to the
  new pythonjsonlogger.json formatter path (the old pythonjsonlogger.jsonlogger
  module is deprecated).
  (#102)