Unify base class using new-style (object).

architectures/tensorflow_components/heads.py

@@ -28,7 +28,7 @@ def normalized_columns_initializer(std=1.0):
     return _initializer
 
 
-class Head:
+class Head(object):
     def __init__(self, tuning_parameters, head_idx=0, loss_weight=1., is_local=True):
         self.head_idx = head_idx
         self.name = "head"