Initialize logging before loading siteconfig.

My recent change to improve test times by reducing initialization ended
up swapping the log.init_logging() call and load_site_config(). This
resulted in a lot of annoying log messages for many commands, such as
`manage.py evolve`. This change restores the order.
Change the format for the indentation info keys.

The key used for recording indentation line pairs was a tuple.
Python is fine with this, but the JSON serializer was not. Instead, we
now serialize it to a string, which is safer.