ffwd should support datadog statsd

[miketheman]

The current datadog plugin uses the HTTPS module to submit metrics over HTTPS to the datadog metrics api endpoint.

Datadog supports use of a local Agent, which serves as a StatsD server, accepting packets in the dogstatsd format, allowing applications to not block when submitting metrics, rather preferring using local UDP sockets to ship the data.

See:

• http://docs.datadoghq.com/guides/dogstatsd/
• https://github.com/DataDog/dogstatsd-ruby

[udoprog]

FFWD's http support is a non-blocking implementation from https://github.com/igrigorik/em-http-request - so blocking itself is not a huge issue as long as datadog can handle the supplied load and responds within the configured batch time period (10s by default).

But sure, it would be neat to be able to support another output (?) plugin. But low prio for now unless someone supplies the code.