CE framework refactor design

[Superjomn]

This version will contain the following enhancement:

• more unittests for better extending and teamworking
• store the KPIs to DB
• more clear abstraction in Python for the data structures in DB
• consistent task-specified argument setting (by environment variable)
• change DB from MongoDB to Redis for simplier usage
• better monitor with
  • unit representation in charts
• with a report for measuring the KPIs change

This refactor will still be compatible with the original kpi.py and all the tasks.