Web UI and dependencies added by it are beyond the updated scope
of Rubick project (see README file for updates of scope).
This change removes components of Web UI (front-end related code)
and components of API service (celery, flask etc).
Update README to reflect the current scope of Rubick project.
blueprint decouple-ui
Change-Id: I302626395c1a677871ac5154f2064bef400be3f1