Make GenericLogger a LoggerAdapter. Expose module loggers by logger_name...

I think the GenericLogger resembles a LoggerAdapter: https://docs.python.org/2/howto/logging-cookbook.html#context-info. Also, I needed more control over logging by module, so I got loggers for each of them based on logger_name. All was going directly into root before.

I didn't find any wreckage nor functionality problems. Feel free to suggest improvements, and thanks for this great django app!