Use tf.layers.dropout. Add gitter badge.

README.md

@@ -2,7 +2,8 @@
 A neural net training interface based on TensorFlow.
 
 [![Build Status](https://travis-ci.org/ppwwyyxx/tensorpack.svg?branch=master)](https://travis-ci.org/ppwwyyxx/tensorpack)
-[![badge](https://readthedocs.org/projects/tensorpack/badge/?version=latest)](http://tensorpack.readthedocs.io/en/latest/index.html)
+[![ReadTheDoc](https://readthedocs.org/projects/tensorpack/badge/?version=latest)](http://tensorpack.readthedocs.io/en/latest/index.html)
+[![Gitter chat](https://badges.gitter.im/gitterHQ/gitter.png)](https://gitter.im/tensorpack/users)
 
 See some [examples](examples) to learn about the framework:
 

tensorpack/models/regularize.py

@@ -95,5 +95,5 @@ def Dropout(x, keep_prob=0.5, is_training=None, noise_shape=None):
     """
     if is_training is None:
         is_training = get_current_tower_context().is_training
-    keep_prob = tf.constant(keep_prob if is_training else 1.0)
-    return tf.nn.dropout(x, keep_prob, noise_shape=noise_shape)
+    return tf.layers.dropout(
+        x, rate=1 - keep_prob, noise_shape=noise_shape, training=is_training)