Implement Status Change

[yw8077]

As a developer I need to be able to change between CREATED, PROCESSING, and COMPLETED So that the status of the order can be managed effectively

Details and Assumptions

• The system should allow the status of an order to be changed only in valid state transitions: CREATED -> PROCESSING PROCESSING -> COMPLETED

• Orders should not be able to transition directly from CREATED to COMPLETED or from COMPLETED to any other state.

  Acceptance Criteria

  When I change the status of the order 
  Then the status should be updated