feat(subsonic): return playCount in album responses

closes #458

server/ctrlsubsonic/spec/construct_by_tags.go

@@ -51,6 +51,9 @@ func NewAlbumByTags(a *db.Album, artists []*db.Artist) *Album {
 	for _, g := range a.Genres {
 		ret.Genres = append(ret.Genres, &GenreRef{Name: g.Name})
 	}
+	if a.Play != nil {
+		ret.PlayCount = a.Play.Count
+	}
 	return ret
 }
 

server/ctrlsubsonic/spec/spec.go

@@ -144,6 +144,7 @@ type Album struct {
 	Name       string        `xml:"name,attr"              json:"name"`
 	TrackCount int           `xml:"songCount,attr"         json:"songCount"`
 	Duration   int           `xml:"duration,attr"          json:"duration"`
+	PlayCount  int           `xml:"playCount,attr"          json:"playCount"`
 	Genre      string        `xml:"genre,attr,omitempty"   json:"genre,omitempty"`
 	Genres     []*GenreRef   `xml:"genres,omitempty"       json:"genres,omitempty"`
 	Year       int           `xml:"year,attr,omitempty"    json:"year,omitempty"`