1. refine quick start and pipeline doc
2. remove tf pytorch easynlp from requirements
3. lazy import for torch and tensorflow
4. test successfully on linux and mac intel cpu
5. update api doc

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/8882373

* add trainer interface
 * add trainer script
 * add model init support for pipelineadd pipeline tutorial and fix bugs 
 * add text classification evaluation to maas lib 
 * add quickstart and prepare env doc
 * relax requirements for torch and sentencepiece
 * merge release/0.1 and fix conflict
 * modelhub support for model and pipeline

 Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/8868339

* add preprocessor module
 * add model base and builder
 * update task constant
 * add load image preprocessor and its dependency
 * add pipeline interface and UT covered
 * support default pipeline for task
 * add image matting pipeline
 * refine nlp tokenize interface
 * add nlp pipeline 
 * fix UT failed
 * add test for Compose

Link: https://code.aone.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/8769235

* add preprocessor module

* add test for Compose

* fix citest error

* fix abs class error

* add model base and builder

* update task constant

* add load image preprocessor and its dependency

* add pipeline interface and UT covered

* support default pipeline for task

* refine models and pipeline interface

* add pipeline folder structure

* add image matting pipeline

* refine nlp tokenize interface

* add nlp pipeline 

1.add preprossor model pipeline for nlp text classification
2. add corresponding test

Link: https://code.aone.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/8757371

* new nlp pipeline

* format pre-commit code

* update easynlp pipeline

* update model_name for easynlp pipeline; add test for maas_lib/utils/typeassert.py

* update test_typeassert.py

* refactor code

1. rename typeassert to type_assert
2. use lazy import to make easynlp dependency optional
3. refine image matting UT

* fix linter test failed

* update requirements.txt

* fix UT failed

* fix citest script to update requirements

* add license
* add folder structure

Link: https://code.aone.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/8682838