change argument in network.py to adapt to new changes in tensorflow

Author: chiachunlu

kaffe/tensorflow/network.py

@@ -177,7 +177,7 @@ def lrn(self, input, radius, alpha, beta, name, bias=1.0):
 
     @layer
     def concat(self, inputs, axis, name):
-        return tf.concat(values=inputs, concat_dim=axis,  name=name)
+        return tf.concat(values=inputs, axis=axis,  name=name)
 
     @layer
     def add(self, inputs, name):