Gauge not working with graphite reporter

[ankitchiplunkar]

The gauge metric is not working with the graphite_reporter.

To recreate the issue:

1. Run graphite container:

   docker run \
   -d \
   --name graphite \
   --restart=always \
   --network host\
   -p 80:80 \
   -p 8080:8080 \
   -p 2003-2004:2003-2004 \
   -p 2023-2024:2023-2024 \
   -p 8125:8125/udp \
   -p 8126:8126 \
   -v /tmp/data/graphite/configs:/opt/graphite/conf \
   -v /tmp/data/graphite/data:/opt/graphite/storage \
   -v /tmp/data/graphite/statsd:/opt/statsd \
   graphiteapp/graphite-statsd

2. Send some metrics to the graphite container, using getSampleReport from helper.js in test/usint:

   
   const metrics = require("metrics"),
   Report = metrics.Report,
   Counter = metrics.Counter,
   Timer = metrics.Timer,
   Meter = metrics.Meter,
   Histogram = metrics.Histogram,
   CachedGauge = metrics.CachedGauge

function getSampleReport() { var counter = new Counter(); counter.inc(5); var timer = new Timer(); for (var i = 1; i <= 100; i++) { timer.update(i); } var meter = new Meter(); meter.mark(10); var hist = new Histogram(); for (var i = 1; i <= 100; i++) { hist.update(i*2); } var gauge = new CachedGauge(function () { return 0.8 }, 10000); var report = new Report(); report.addMetric("basicCount", counter); report.addMetric("myapp.Meter", meter); report.addMetric("myapp.Timer", timer); report.addMetric("myapp.Histogram", hist); report.addMetric("myapp.Gauge", gauge); return report; }

const report = getSampleReport(); const reporter = new metrics.GraphiteReporter(report, "test", "localhost", 2003); reporter.start(1000);

3. Run the test and send data to graphite

node test.js

4. Checkout graphite browser at `localhost:8080`

![image](https://user-images.githubusercontent.com/5904910/49378668-76871580-f70d-11e8-8d30-3a9b46bc97d0.png)

The Gauge folder is missing from graphite, i.e. gauge data was not sent to graphite container

[tolbertam]

Fixed by #65 and released in v0.1.20, thank you!