* 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