in the metric_tank handler, skip over nil metrics that get send in
in the metric_tank handler, skip over nil metrics that get send in

raintank/metrictank,raintank/raintank-metric,raintank/metrictank,replay/metrictank,OOM-Killer/metrictank,replay/metrictank,raintank/raintank-metric,raintank/metrictank,replay/metrictank,OOM-Killer/metrictank,raintank/metrictank,raintank/raintank-metric,replay/metrictank,OOM-Killer/metrictank