stealthly/gokafkaclient task runner

Implemented to run stealthly/go_kafka_client. Exposes stack variables:

• $app.host - stealthly/go_kafka_client scheduler address.
• $app.port - stealthly/go_kafka_client scheduler port.
• $app.api - stealthly/go_kafka_client scheduler api address in a form http://$host:$port.

For $app == gokafka variables would be:

• gokafka.host, gokafka.port and gokafka.api for scheduler.