Graylog2 Extended Format Decoder

A simple decoder for the Graylog2 Extended Format for logging based on some code I saw in a blog @trink had assisted with. This should work with the specification for GELF. The logical next step would be a Graylog Output for the server but it is sufficient for my uses to simply ingest GELF so it can be tossed at ES+Kibana.
It was recently updated in the docs (not sure why rtd has not picked it up)
https://github.com/mozilla-services/heka/blob/dev/docs/source/message/index.rst