CBQE-2450: n1ql fix joins syntax changes

Change-Id: I303b094a9696ce4f3b2932f04655975d802985c4
Reviewed-on: http://review.couchbase.org/42620
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>