Logger
#constructor
should return an emitter
should handle types option
should register log methods for all types
should register levels for all types
#[type]
should emit type events
type
#prefix
should return a timestamp
#_format
should join string arguments
should add a newline
#pipe
should write logs to stream
should remove listeners on close
should handle logLevel option
logger
should return a Logger instance
should export Logger class