add replication latency test with high rate of write operations
add replication latency test with high rate of write operations

Change-Id: I390c4818806f9e9046d1cd511c2c5a4fe3f3ad18
Reviewed-on: http://review.couchbase.org/39238
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>

couchbase/perfrunner,EricACooper/perfrunner,pavel-paulau/perfrunner,vmx/perfrunner,thomas-couchbase/perfrunner,pavel-paulau/perfrunner,hsharsha/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,vmx/perfrunner,PaintScratcher/perfrunner,couchbase/perfrunner,couchbase/perfrunner,dkao-cb/perfrunner,couchbase/perfrunner,PaintScratcher/perfrunner,mikewied/perfrunner,EricACooper/perfrunner,thomas-couchbase/perfrunner,couchbase/perfrunner,hsharsha/perfrunner,dkao-cb/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,EricACooper/perfrunner,mikewied/perfrunner,EricACooper/perfrunner