Add option for disabling the double translation of timer metrics in statsd

[matthewbogner]

When a "Gauge" (in statsd lingo) is sent over, statsd will compute a bunch of trends and percentile calculations for each metric. With Yammer Metrics timers and histograms, those calculations are already there, so there is no need for statsd to calculate them again.

This commit provides an option that allows statsd to just take the metrics as provided by the metrics registry and pass them along to graphite un-altered.

This commit is backwards compatible.

If merged, please kindly perform a new 2.3.1 release to maven central.

[fluential]

Any progress on that one? Would be nice to have this merged.

[tburch]

This would be nice to have!

[jmason]

I've just run into this -- this is still an outstanding bug, and the pull req should be applied if possible.