CBQE-1197 Add wait for persistence to view tests

Change-Id: Ic7388627c0aa5334448214c5b04426c3e5938539
Reviewed-on: http://review.couchbase.org/25814
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>