Add Middleware for correlation_id

The middleware generates the 'correlation_id' if it is not already present
in the request header. This 'correlation_id' can be used to enable more
effective debugging of requests that span multiple services.

Implements: blueprint create-a-unified-correlation-id

Change-Id: Ibc06a5b05b628e0b640e9299c79127ecbf9c684e
Merge "Add Middleware for correlation_id"