Yet another ResNet (#4298)

* deprecate research/resnet

* also add a tf warning in the code

research/resnet/README.md

 <font size=4><b>Reproduced ResNet on CIFAR-10 and CIFAR-100 dataset.</b></font>
 
+# Deprecated
+This code is not actively maintained. Please use the
+[offical ResNet](https://github.com/tensorflow/models/tree/master/official/resnet) implementation
+instead.
+
 Xin Pan
 
 <b>Dataset:</b>

research/resnet/resnet_model.py

@@ -35,6 +35,10 @@ HParams = namedtuple('HParams',
                      'relu_leakiness, optimizer')
 
 
+tf.logging.warning("models/research/resnet is deprecated. "
+                   "Please use models/official/resnet instead.")
+
+
 class ResNet(object):
   """ResNet model."""