Reuse Telegraf Output plugins

When using Kapacitor, transformed data can be sent to an influxdb server. Such a neat feature!

[Kapacitor](https://github.com/influxdata/kapacitor) has a single output plugin : [InfluxDbOut](https://docs.influxdata.com/kapacitor/v0.11/nodes/influx_d_b_out_node/).

However [Telegraf](https://github.com/influxdata/telegraf/) has more than [15 output plugins](https://github.com/influxdata/telegraf/tree/master/plugins/outputs).

Please note that even for InfluxDb output, Telegraf ([influxdb.go](https://github.com/influxdata/telegraf/blob/master/plugins/outputs/influxdb/influxdb.go)) has more configuration than Kapacitor ([influxdb_out.go](https://github.com/influxdata/kapacitor/blob/master/pipeline/influxdb_out.go)).

If Kapacitor does not have the same output plugins, it means that Telegraf users cannot use the kapacitor output functionnality.

As part of the same [TICK stack](https://influxdata.com/get-started/what-is-the-tick-stack/), I would recommend to leverage the Telegraf output plugins in Kapacitor.

Compare Kapacitor's pipeline/influxdb_out.go with Telegraf's plugins/outputs/influxdb/influxdb.go and the broader plugins/outputs directory. Start by understanding how the existing InfluxDB output is configured, then determine the integration scope for reusing additional Telegraf output plugins. Done means the agreed output plugins are available through Kapacitor with suitable configuration and behavior.

Written by the indexing model from the issue text.