use lumberjack for log rolling

This is very similar to the last PR, except I didn't change out the upstart config stuff... since the output redirect doesn't hurt anything, and we need the rest of the code to properly set permissions and owner on the logfile.
I'd be tempted to make magic numbers like this consts or vars - in the package. Although I guess as far as the compiler is concerned it would be a waste. Probably ok to leave this as it is