JCBC-489: Add support for replica read.

Change-Id: I3383648e962624424c448044b54f43d90c2e092e
Reviewed-on: http://review.couchbase.org/39265
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>