Re-design topic-to-influxdb support in a general way

[michal-harish]

Before Kafka Connect existed we had the InfluxDB Loader which supported consumer configuration. It would then start a KafkaMetrics consumer that would publish the measurements to InfluxDB. From version 0.9 we have introduced Metrics Connect which implements the connector but the general feature was not designed at the abstract level as "topic-to-influxdb mechanism" but was bundled with the idea of InfluxDB Loader. This should be re-designed in such way that there is an interface representing the abstract level features which is then implemented via the means of either Consumer or Connector depending on version.

[michal-harish]

The other thing that needs to be considered is that sometimes in post 0.10.x releases, embedded support for Kafka Connect will be available but this is not the case in 0.9.x and 0.10.0 versions. This embedded support could make the interface of the general function a bit easier to define but because this is not available versions 0.9.x and 0.10.0 the design has to accommodate both cases.