Moved queryport-client files to client/ subpkg.

This is to reduce the possibility of circular dependency.

Change-Id: I6eed286e253805112e9b8c95a9d7dd66f4a0281a
Reviewed-on: http://review.couchbase.org/43707
Reviewed-by: Sriram Melkote <siri@couchbase.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>