Install blinker package
Define User model callbacks
Register user model callbacks
Write User model spec
Write UCB model spec
Create UCB model
Calculate UCB after clicking an article
Write CalculateUCB interactor spec
Implement CalculateUCB interactor by spec
Calculate UCB after recommendation
Change class name
Install boto package
Add aws config
Add sns config
Add a script to polling sqs
Merge branch 'dev-collect-experiment-data'