added Artists filter

MediaBrowser.Controller/Entities/Audio/Artist.cs

@@ -14,5 +14,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         {
             return "Artist-" + Name;
         }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether this instance is on tour.
+        /// </summary>
+        /// <value><c>true</c> if this instance is on tour; otherwise, <c>false</c>.</value>
+        public bool IsOnTour { get; set; }
     }
 }

MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs

@@ -139,5 +139,15 @@ namespace MediaBrowser.Controller.Entities.Audio
                 base.Images = value;
             }
         }
+
+        /// <summary>
+        /// Determines whether the specified artist has artist.
+        /// </summary>
+        /// <param name="artist">The artist.</param>
+        /// <returns><c>true</c> if the specified artist has artist; otherwise, <c>false</c>.</returns>
+        public bool HasArtist(string artist)
+        {
+            return Children.OfType<Audio>().Any(i => i.HasArtist(artist));
+        }
     }
 }