local: Reintroduce local/data_dir config for the 1.1.x series

As to not break compat with mopidy-local-* in v1.1.1.

mopidy/local/__init__.py

@@ -23,7 +23,7 @@ class Extension(ext.Extension):
         schema = super(Extension, self).get_config_schema()
         schema['library'] = config.String()
         schema['media_dir'] = config.Path()
-        schema['data_dir'] = config.Deprecated()
+        schema['data_dir'] = config.Path(optional=True)
         schema['playlists_dir'] = config.Deprecated()
         schema['tag_cache_file'] = config.Deprecated()
         schema['scan_timeout'] = config.Integer(

mopidy/local/ext.conf

@@ -2,6 +2,7 @@
 enabled = true
 library = json
 media_dir = $XDG_MUSIC_DIR
+data_dir = $XDG_DATA_DIR/mopidy/local
 scan_timeout = 1000
 scan_flush_threshold = 100
 scan_follow_symlinks = false