dbus: music_track_listener should also listen for Rhythmbox's changing stream titles

[lirel]

When playing Streaming-Music in Rhythmbox changing-song-titles are not shown to Gajim-users and contacts, instead the name of the stream is shown, and often doesn't change for hours. Often there is no artist given what makes the statusfield looking crapy. irc:moch@irc.gnome.org/#rhythmbox said(chatlog http://gajim.pastebin.com/887712 ) gajim should ask for playingSongPropertyChanged and should read from rb:stream-song-title

The behaviour should be: In the beginning show the Stream-Title and when the song-title changes the song-title and the artist should be shown.

[asterix]

could you copy / paste this chatlog here as pastebin doesn't have it anymore :/

[asterix]

(In [8437]) listen to Rhythmbox's changing stream titles. fixes #3013

[asterix]

(In [8714]) listen to Rhythmbox's changing stream titles. fixes #3013