Add more OpenSubsonic fields

- mediaType
- musicBrainzId (Child)

server/subsonic/responses/.snapshots/Responses AlbumWithSongsID3 with data should match .JSON

@@ -8,8 +8,8 @@
     "id": "1",
     "name": "album",
     "artist": "artist",
-    "userRating": 0,
     "genre": "rock",
+    "userRating": 0,
     "genres": [
       {
         "name": "rock"
@@ -29,14 +29,6 @@
         "track": 1,
         "year": 1985,
         "genre": "Rock",
-        "genres": [
-          {
-            "name": "rock"
-          },
-          {
-            "name": "progressive"
-          }
-        ],
         "coverArt": "1",
         "size": 8421341,
         "contentType": "audio/flac",
@@ -47,8 +39,18 @@
         "duration": 146,
         "bitRate": 320,
         "isVideo": false,
+        "mediaType": "song",
+        "musicBrainzId": "4321",
         "bpm": 127,
-        "comment": "a comment"
+        "comment": "a comment",
+        "genres": [
+          {
+            "name": "rock"
+          },
+          {
+            "name": "progressive"
+          }
+        ]
       }
     ]
   }