Allow INI/JSON/YAML confifuration for logging

Hi,

I noticed https://github.com/mozilla-services/circus/issues/366 and I wondered whether something like this would be a viable approach.  I have an example syslog configuration file that seems to work with this patch: https://gist.github.com/jwal/8258682

The idea is that you can use the --logger-config option on circusd (or the loggerconfig option in the circus section of the circus.ini file) to provide the path to a logging configuration file in a standard Python format.  The full description for this configuration file format is here: http://docs.python.org/2/howto/logging.html

Thoughts?  Questions? Ideas?

Regards,

James