Implement an endpoint route to expire a Promotion

[ahbbzong]

**As a developer
**I need to implement an endpoint route to expire a Promotion
**So that I can expire a promotion.

Details & Assumptions:
We need to create a new route.py file and come up with a new def for the action method. We need to change the state of the promotions by restful call.

Acceptance Criteria:
The restful call could successfully change the state of each promotion.

Given a promotion
When running the restful call as test case
Then make sure the state of the promotion successfully changed.