Fix: getPlayed method not returning good values

Hey,

Just a really small fix for the getPlayed method which doesn't return good values at all.
I've been using that fix for months and…forgot to send a patch. ^^'

It's currently running on http://www.songaccoustic.fr, this function is used to "scrobble" musics (when to consider a music as listened) and it works flawlessly with this patch.

Thanks for that great lib. =)