unittest for demo service
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/10006180

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9662182

    * clean up test level

修复master分支ocr_detection 单元测试bug
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9112290

    * create ocr_detection task

* fix code check error

* fix code check error

* fix code check issue

* fix code check issue

* replace c++ nms with python version

* fix code check issue

* fix code check issue

* rename maas_lib

* merge master to ocr/ocr_detection

* add model_hub sup for ocr_detection

* fix bug

* replace c++ decoder with python version

* fix bug

* Merge branch 'master' into ocr/ocr_detection

* merge master

* fix code check

* update

* add requirements for ocr_detection

* fix model_hub fetch bug

* remove debug code

* Merge branch 'master' into ocr/ocr_detection

* add local test image for ocr_detection

* update requirements for model_hub

* Merge branch 'master' into ocr/ocr_detection

* fix bug for full case test

* remove ema for ocr_detection

* Merge branch 'master' into ocr/ocr_detection

* apply ocr_detection test case

* Merge branch 'master' into ocr/ocr_detection

* update slim dependency for ocr_detection

* add more test case for ocr_detection

* release tf graph before create

* recover ema for ocr_detection model

* fix code

* Merge branch 'master' into ocr/ocr_detection

* fix code

合并model hub 代码
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9096493

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/8967432

* create ocr_detection task

* replace c++ nms with python version

* replace c++ decoder with python version

* add requirements for ocr_detection