[FIX] drop-out option warning

[ruohoruotsi]

Fix drop-out option warning, esp. as its distracting and muddies the output of the Jupyter prediction notebook.

/Users/iroro/anaconda3/lib/python3.6/site-packages/torch/nn/modules/rnn.py:46: 
UserWarning: dropout option adds dropout after all but last recurrent layer,
so non-zero dropout expects num_layers greater than 1, 
but got dropout=0.3 and num_layers=1 "num_layers={}".format(dropout, num_layers))