add sync_latency to base report
add sync_latency to base report

Change-Id: Ib9672415e41c03f69b380aacf63404996f2fbb26
Reviewed-on: http://review.couchbase.org/31239
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>

couchbase/cbmonitor,couchbase/cbmonitor