* Add "client-api-objects" dependency for xpack plugin and transport-client
This adds another gradle project, "client-api-objects" which is intended to be a
common dependency so that the xpack plugin and transport-client can share the
same Request and Response objects.
Relates to elastic/x-pack-elasticsearch#2925
Original commit: elastic/x-pack-elasticsearch@a6d83299d0
Lee Hinman