Emit Buffer data direct from node-microphone

[rhysmorgan134]

Hi, this is a super basic PR, it creates an event emitter on microphone data that sends the raw buffer out of node-microphone via an event emitter. It's super useful in cases like mine of node-carplay. It allows me to add format data to the buffer, and then pass on. Without this everytime I start/stop the microphone, I need to create a new stream, and re-instantiate the event listeners to that stream.