format fix for recurrent

Author: JingqingZ

tensorlayer/layers/recurrent.py

@@ -271,7 +271,6 @@ class SimpleRNN(RNN):
     -----
     Input dimension should be rank 3 : [batch_size, n_steps, n_features], if no, please see layer :class:`Reshape`.
 
-
     """
 
     def __init__(
@@ -345,7 +344,6 @@ class GRURNN(RNN):
     -----
     Input dimension should be rank 3 : [batch_size, n_steps, n_features], if no, please see layer :class:`Reshape`.
 
-
     """
 
     def __init__(
@@ -419,7 +417,6 @@ class LSTMRNN(RNN):
     -----
     Input dimension should be rank 3 : [batch_size, n_steps, n_features], if no, please see layer :class:`Reshape`.
 
-
     """
 
     def __init__(