We should be able to send metrics to a variety of places other than InfluxDB. This means that we'll need to have some sort of framework for defining new output sinks. This also means that we should be able to disable sending metrics to any of these output sinks, including InfluxDB.

What I'm thinking is to pull the InfluxDB settings into another area like outputs. Then, like plugins, define a number of different outputs where metrics can be sent to.

For Kafka, we should send metrics using the line protocol. This should be fairly simply using the InfluxDB client to convert the metrics to their line protocol equivalents.

The work to add support for Riemann (#34) will also need this output sink implementation.