fix: make sure track has correct discNumber and trackNumber when using AlbumBrowse
fix: make sure track has correct discNumber and trackNumber when using AlbumBrowse

- if track was already cached by a non-AlbumBrowse request, then it would always report discNumber as 0, even if obtained as part of an AlbumBrowse
- try to update the AlbumBrowse fields whenever we get a cached track

andyvand/cocoalibspotify,andyvand/cocoalibspotify,yingwang/Fspot,spotify/cocoalibspotify,spotify/cocoalibspotify,andyvand/cocoalibspotify,yingwang/Fspot,spectralmind/cocoalibspotify,spotify/cocoalibspotify,spectralmind/cocoalibspotify,CrowdTunes/cocoalibspotify,andyvand/cocoalibspotify,spectralmind/cocoalibspotify,CrowdTunes/cocoalibspotify,spotify/cocoalibspotify,CrowdTunes/cocoalibspotify,yingwang/Fspot,CrowdTunes/cocoalibspotify,spectralmind/cocoalibspotify