* Python Environment: add gevent based WSGI server framework
This supply gevent based WSGI server framework to Python Environment, to
allow customer to run their functions under multi-threads.
* classify the flask based application
This set up the flask based application as individual class, to make
sure the consistent and integrity.
* Add instruction of WSGI server selection applied in Python Environment
* Python Environment starting logger: provide framework name
* Add readiness probe
* Remove builder manager http api interface since we don’t use/need it
* Check environment builder status and block build requests until builder is ready
* Replace deprecated api extension interface
* Add healthy check to python env
