Merge pull request #18 from slogsdon7/master

Fix m4a label tag. #12

Author: sampsyo

mediafile.py

@@ -1761,8 +1761,9 @@ def update(self, dict):
     )
     label = MediaField(
         MP3StorageStyle('TPUB'),
-        MP4StorageStyle('----:com.apple.iTunes:Label'),
+        MP4StorageStyle('----:com.apple.iTunes:LABEL'),
         MP4StorageStyle('----:com.apple.iTunes:publisher'),
+        MP4StorageStyle('----:com.apple.iTunes:Label', read_only=True),
         StorageStyle('LABEL'),
         StorageStyle('PUBLISHER'),  # Traktor
         ASFStorageStyle('WM/Publisher'),