Replace Log classes with Loggers classes

To simplify things, avoid interleaved messages and take advantage of runit's default behavior I am replacing ChefInit::Log::Reader and ChefInit::Log::Writer with ChefInit::Loggers. These are loggers that will read from STDIN and send the logs to various destinations. Right now, the only solution we have is for writing to STDOUT.
Bump version to 0.4.0.dev
Update dep on Chef; rely on Chef for mixlib deps