This changeset integrates contextual logging into the registry web application.
Idiomatic context use is attempted within the current webapp layout. The
functionality is centered around making lifecycle objects (application and
request context) into contexts themselves. Relevant data has been moved into
the context where appropriate. We still have some work to do to factor out the
registry.Context object and the dispatching functionality to remove some
awkward portions.
The api tests were slightly refactored to use a test environment to eliminate
common code.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
