Evaluate the WERs of open ASR APIs

Dependencies:

• iflytek API，see openasr/xunfei/README.md
• google cloud API, see openasr/google/README.md
• baidu API，see openasr/baidu/README.md
• tencent API，see openasr/tencent/README.md

Usage:

• apply the open API and set the secret key in 'openasr/config.py'
• prepare the dataset as testdata/dataset, including 'text', 'wav.scp', 'utt2dur' three files.
• run 'openasr/run_dataset.py' to recognize the wavs and compute WER.