emit 'error' events for ws.send() errors

it can throw...
update play.js example
if the websocket connections closes, call disconnect()
don't print out the user's password in debug mode

nobody wants to see that shit
implement sendTrackEnd() function

sends the "sp/track_end" command so that we can play > 3 tracks
example: add playAlbum.js example

Plays all the tracks from a spotify:album uri out of the speakers
example: disconnect from spotify after the track in play.js
implement sendTrackEvent() function
implement sendTrackProgress() function