train chunker default filename fix
train chunker default filename fix

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branch : py3

ephillipe/nltk-trainer,fengzhyuan/nltk-trainer,VinACE/nltk-trainer,fengzhyuan/nltk-trainer,japerk/nltk-trainer,japerk/nltk-trainer,mayk93/nltk-trainer,mayk93/nltk-trainer,VinACE/nltk-trainer,ephillipe/nltk-trainer