Created by: wanghaoshuang

fix #591 (closed) A test result on random dummy data as below:

-----------  Configuration Arguments -----------
batch_size: 16
device: -1
l2: 0.0005
learning_rate: 0.001
max_clip: 10.0
min_clip: -10.0
momentum: 0.9
pass_num: 16
------------------------------------------------
Pass[0], batch[0]; loss: 2614.78; edit distance: 185.0.
End pass[0]; train data edit_distance: 11.5625.
End pass[0]; test data edit_distance: 5.25.
Pass[1], batch[0]; loss: 1669.92; edit distance: 752.0.
End pass[1]; train data edit_distance: 47.0.
End pass[1]; test data edit_distance: 5.0625.