SIANXKE-178: 'details' column + test fix (message_only handler)

[anx-abruckner]

• new column 'details' (JSONField) in StatusLog model
• fixed logging handler for test
• README update

[zhangshine]

Great PR, but JSONField is not supported by all db engines. And I just want to keep this package small and simple.

[nezhar]

Great PR, but JSONField is not supported by all db engines. And I just want to keep this package small and simple.

Would you consider dropping support for outdated Python and Django releases?

• https://endoflife.date/django
• https://endoflife.date/python

The security support of Django 2.2 ends on 01 Apr 2022 and since Django 3.1 the JSONField has been added for all supported database backends: https://docs.djangoproject.com/en/3.1/releases/3.1/#jsonfield-for-all-supported-database-backends

A compatibity matrix can also be added, just in case somebody wants to use the package in combination with an older release, here is an example.

[nezhar]

#38 implements the sugestions above with the current acitve versions of Python and Django.