Picking max_sequence_length in run_classifier.py CoLA task
Is there an upper bound for the max_sequence_length parameter when using run_classifier.py with CoLA task?

When I tested with the default max_sequence_length of 128, everything worked good, but once I changed it to something else, eg 1024, it started the training and failed on the first iteration with the error shown below:
````
Traceback (most recent call last):
  File "run_classifier.py", line 643, in <module>
    main()
  File "run_classifier.py", line 551, in main
    loss = model(input_ids, segment_ids, input_mask, label_ids)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/modules/module.py", line 477, in __call__
    result = self.forward(*input, **kwargs)
  File "/jet/var/python/lib/python3.6/site-packages/pytorch_pretrained_bert/modeling.py", line 868, in forward
    _, pooled_output = self.bert(input_ids, token_type_ids, attention_mask, output_all_encoded_layers=False)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/modules/module.py", line 477, in __call__
    result = self.forward(*input, **kwargs)
  File "/jet/var/python/lib/python3.6/site-packages/pytorch_pretrained_bert/modeling.py", line 609, in forward
    embedding_output = self.embeddings(input_ids, token_type_ids)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/modules/module.py", line 477, in __call__
    result = self.forward(*input, **kwargs)
  File "/jet/var/python/lib/python3.6/site-packages/pytorch_pretrained_bert/modeling.py", line 199, in forward
    embeddings = self.dropout(embeddings)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/modules/module.py", line 477, in __call__
    result = self.forward(*input, **kwargs)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/modules/dropout.py", line 53, in forward
    return F.dropout(input, self.p, self.training, self.inplace)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/functional.py", line 595, in dropout
    return _functions.dropout.Dropout.apply(input, p, training, inplace)
  File "/jet/var/python/lib/python3.6/site-packages/torch/nn/_functions/dropout.py", line 40, in forward
    ctx.noise.bernoulli_(1 - ctx.p).div_(1 - ctx.p)
RuntimeError: Creating MTGP constants failed. at /jet/tmp/build/aten/src/THC/THCTensorRandom.cu:34
```` 

The command I ran is 

```
python run_classifier.py \
  --task_name CoLA \
  --do_train \
  --do_eval \
  --do_lower_case \
  --data_dir $GLUE_DIR/Test/ \
  --bert_model bert-base-uncased \
  --max_seq_length 128 \
  --train_batch_size 32 \
  --learning_rate 2e-5 \
  --num_train_epochs 3.0 \
  --output_dir /tmp/BERT/test1
````
As mentioned in #89, the maximum value of `max_sequence_length` is 512. <|||||>@rodgzilla thanks!