Refactor Action Endpoint using RestPLUS

[ajita-asthana]

As a Developer
I need to implement Flask-RESTPlus
So that I could generate Swagger Doc with less effort

Details and Assumptions

• follow the file layout outlined in lab-flask-restplus-swagger repo
• Implemenentation for Activate a promotion and Deactivate a promotion endpoints

Acceptance Criteria

Make sure that all HTTP errors return json error messages and not html.
Make sure no 500 errors when throwing bad data
Make sure that your Flask-RESTPlus implementation still works like the original. the same test cases should still work as expected.
Make sure to add Swagger annotation as well