title: UserWarning: Implicit dimension choice for log_softmax has been deprecated
body: <p>I´m using Mac OS el capitán and I am trying to follow the <a href="http://opennmt.net/OpenNMT-py/quickstart" rel="noreferrer">quick start tutorial for OpenNMT pytorch</a> version.  In the training step I get the following warning message:</p>
  
  <pre><code>OpenNMT-py/onmt/modules/GlobalAttention.py:177: UserWarning: Implicit dimension choice for softmax has been deprecated. Change the call to include dim=X as an argument. 
  
  align_vectors = self.sm(align.view(batch*targetL, sourceL))
  /Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/torch/nn/modules/container.py:67: UserWarning: Implicit dimension choice for log_softmax has been deprecated. Change the call to include dim=X as an argument.
    input = module(input)
  </code></pre>
  
  <p>Step 1: Preprocess data (works as expected)</p>
  
  <pre><code>python preprocess.py -train_src data/src-train.txt -train_tgt data/tgt-train.txt -valid_src data/src-val.txt -valid_tgt data/tgt-val.txt -save_data data/demo
  </code></pre>
  
  <p>Step 2: Train model (produces the warning message)</p>
  
  <pre><code>python train.py -data data/demo -save_model demo-model
  </code></pre>
  
  <p>Has anyone come across this warning or have any pointers to solve it?</p>