Populate the position value in Dbus with the position of the song

[luticus]

In the Linux client you already populate many dbus values, which is why KDE can know what song/album/artist are playing and can pull artwork and put it in the system tray. The problem is that you don't populate the position value and thus it always returns 0: 

The relevant dbus location is:
org.mpris.MediaPlayer2.spotify /org/mpris/MediaPlayer2 org.mpris.MediaPlayer2.Player.Position

You can observe the problem by playing a song and, in a terminal, running: 
watch -n 1 qdbus org.mpris.MediaPlayer2.spotify /org/mpris/MediaPlayer2 org.mpris.MediaPlayer2.Player.Position

This means that applications like KDE's system tray have to take their "best guess" at what your current seek position is in the song. This is why when you click the tray widget it populates the seek value from the moment you clicked the widget to display the information and does not show the true value of the song. By simply populating this value you'd fix several Linux desktop widgets instantly to show the correct data.

Thanks!