feat: add support for using dictConfig to configure logging. Basic logging config (one level and one output file non-rotating) was always possible from config.ini. However the LOGGING_CONFIG setting could be used to load an ini fileConfig style file to set various channels (e.g. roundup.hyperdb) (also called qualname or tags) with their own logging level, destination (rotating file, socket, /dev/null) and log format. This is now a deprecated method in newer logging modules. The dictConfig format is preferred and allows disabiling other loggers as well as invoking new loggers in local code. This commit adds support for it reading the dict from a .json file. It also implements a comment convention so you can document the dictConfig. configuration.py: new code test_config.py: test added for the new code. admin_guide.txt, upgrading.txt CHANGES.txt: docs added upgrading references the section in admin_guid.