[yanan] refact the tasks code
[yanan] merge stash
code review v1.
code review v2.
code review v3
code review
[yanan] very minor changes
[yanan] merge code and finish two todo about console.log
[yanan] delete a log and refact the file structure of modules
[yanan] finish individual computation
[yanan] add refactor task
[yanan] finish roomify stats
add api server config .
[yanan] finish room's lessonsituation statistic
[yanan] for merge
[yanan] finish video computation
[yanan] change async task count to 3
[yanan] 1. finishProblemSet algorithm; 2. wrong data recorection
[yanan] finish multi db function
[yanan] add startproblemset stats