Configure interaction with Kafka

The interaction between MAIA and Kafka is defined in an yml-file

installation path/sysconfig.db/maia_core/kafka_conf.yml

The file kafka_conf.yml is installed with a default configuration that connects MAIA to a local kafka server on port 9092

MAIA is also by default configured to listen to kafka topic 'MAIA'

Changes made to kafka_conf.yml must be followed by a restart of maia_core (command 'ipv maia_core restart).