Add package name and specs
First iteration

10 minutes with ping pong pairing
Add a service for implements following users feature
Use same service for users registration and followings

Refactor :metal:
Take account about unregistered users
Extract users repository
Extract a factory
Add a new repository for keeping users in a durable state
Third iteration: Make data durable
Add an HTTP delivery mechanism
Use tornado instead of flask
Remve duplicated spec
Implement 5th iteration
Add cos publication to HTTP delivery mechanism
Implement durable solution to co's publication
Use durable repository in webapp
Return None if user does not exists
Store user when publishing a new co