Indentation error

Spun out of #1981 as [requested](https://github.com/tensorflow/models/pull/1981#issuecomment-316833033) by @derekjchow

Also, should there be __commas__ at the end of lines: 82, 84, 86, 88, 90, 92, and 94?

object_detection/utils/label_map_util_test.py

@@ -75,7 +75,7 @@ class LabelMapUtilTest(tf.test.TestCase):
     with self.assertRaises(ValueError):
       label_map_util.load_labelmap(label_map_path)
 
-    def test_keep_categories_with_unique_id(self):
+  def test_keep_categories_with_unique_id(self):
     label_map_proto = string_int_label_map_pb2.StringIntLabelMap()
     label_map_string = """
       item {