The purpose of the document staging api is to provide a client of
shipyard to ingest and manipulate documents within the UCP platform
In support of the need to reach out to other services, this change
also introduces the use of keystone for service discovery and connection
to other UCP services.
Change-Id: I6fa113f8786cad2884c0b791788a4ef40cd1a6b6
3ac47328c3