Add id2label and label2id mappings

config.json

@@ -1,7 +1,18 @@
 {
-  "num_labels": 4, 
+  "num_labels": 4,
   "model_type": "resnet",
   "architectures": ["ResNetForImageClassification"],
   "hidden_size": 2048,
-  "labels": ["level0", "level1", "level2", "level3"]
+  "id2label": {
+    "0": "level0",
+    "1": "level1",
+    "2": "level2",
+    "3": "level3"
+  },
+  "label2id": {
+    "level0": 0,
+    "level1": 1,
+    "level2": 2,
+    "level3": 3
+  }
 }