* Log request id from the request context for glance-api
and glance-registry
* Further integrate with the common log module by storing RequestContext
objects in thread-local storage so loggers can acces their attributes
* Move request id formatting into the request module so it appears with
the preferred prefix (req-) in logs
* Implement bp glance-request-tracking
Change-Id: I2095ad16fef6b4bc8e49229c9f0326da8c743ff7
a0689d2b45