Sync request_id middleware for nova

This piece of middleware generates and attaches a request_id to
a request, to be used in completing the blueprint
cross-service-request-id for icehouse.
See change Ib4a9c404cb149d8f76bde52f7613a9596b2233b9

Change-Id: Ib0b0f19b3be332f736246b472902c6b95c1264e9
Implements: blueprint cross-service-request-id
Merge "Sync request_id middleware for nova"