Measure 99.9th percentile latency
Measure 99.9th percentile latency

Change-Id: I2609c051d3eacc45b02aaffdf8c98251bae71b7c
Reviewed-on: http://review.couchbase.org/82229
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>

couchbase/perfrunner,couchbase/perfrunner,couchbase/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner