Properly integrate with Tox logging/reporter functionality

[enpaul]

I suspect that this plugin is not using Tox's logging/reporter functionality properly. I suspect this because I haven't actually looked at how to do it properly. The current usage of Tox's reporter module in the plugin is trivially functional, which is all I needed, but it should be updated to log to the proper environment logger.

I need to take a closer look at Tox's logging/reporter functionality and find a better way to log the main display messages (currently the reporter.verbosity0(...) calls in the plugin). I haven't been able to find anything in the Tox documentation about the logging model so I expect other plugins and the source for tox.reporter will be the best resources.