title: Attribute error while loading vocabulary wrapper
body: <p>While trying to work with text to image based on <a href="https://github.com/Wangt-CN/Code_CASC" rel="nofollow noreferrer">this</a> model,I get the following attribute error in train.py:</p>
  <pre><code> 17 
   18     # Load Vocabulary Wrapper
  ---&gt; 19     vocab = deserialize_vocab(os.path.join(opt.vocab_path, '%s_vocab.json' % opt.data_name))
       20     opt.vocab_size = len(vocab)
       21 
  
  AttributeError: 'Namespace' object has no attribute 'vocab_path'
  </code></pre>
  <p>The deserialization function in vocab.py:</p>
  <pre><code>def deserialize_vocab(src):
      with open(src) as f:
          d = json.load(f)
      vocab = Vocabulary()
      vocab.word2idx = d['word2idx']
      vocab.idx2word = d['idx2word']
      vocab.idx = d['idx']
      return vocab
  </code></pre>