Making it not break if webkitAudioContext isn't present

Sorry for all the whitespace diffs. Also, i just ran node build and the other changes to the demo were the result. Perhaps you hadn't built with the latest changes or I've got a different browserify version or something.

Anyway, main thing that I was trying to do was make it return early if no webkit audio context. Also by returning the emitter, consuming code wouldn't need to be modified (they'd just never get the events).