add charts with rolling percentile of score

where 90th percentile is used as score

Change-Id: I26aedd6b75f0fd0249efdc85dfa18988ed7a7d69
Reviewed-on: http://review.couchbase.org/31125
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>