Add wavefront serializer plugin (#5670)

plugins/serializers/wavefront/README.md

@@ -0,0 +1,47 @@
+# Example
+
+The `wavefront` serializer translates the Telegraf metric format to the [Wavefront Data Format](https://docs.wavefront.com/wavefront_data_format.html).  
+
+### Configuration
+
+```toml
+[[outputs.file]]
+  files = ["stdout"]
+
+  ## Use Strict rules to sanitize metric and tag names from invalid characters
+  ## When enabled forward slash (/) and comma (,) will be accpeted
+  # use_strict = false
+  
+  ## point tags to use as the source name for Wavefront (if none found, host will be used)
+  # source_override = ["hostname", "address", "agent_host", "node_host"]
+
+  ## Data format to output.
+  ## Each data format has its own unique set of configuration options, read
+  ## more about them here:
+  ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
+  data_format = "wavefront"
+```
+
+### Metrics
+
+A Wavefront metric is equivalent to a single field value of a Telegraf measurement.
+The Wavefront metric name will be: `<measurement_name>.<field_name>`
+If a prefix is specified it will be honored.
+Only boolean and numeric metrics will be serialized, all other types will generate
+an error.
+
+### Example
+
+The following Telegraf metric
+
+```
+cpu,cpu=cpu0,host=testHost user=12,idle=88,system=0 1234567890
+```
+
+will serialize into the following Wavefront metrics
+
+```
+"cpu.user" 12.000000 1234567890 source="testHost" "cpu"="cpu0"
+"cpu.idle" 88.000000 1234567890 source="testHost" "cpu"="cpu0"
+"cpu.system" 0.000000 1234567890 source="testHost" "cpu"="cpu0"
+```