Refreshing osm_metrics stack

Moves Prometheus installation to OSM Core for it to be available for MON Collector.
Sets Prometheus version to v2.4.3
Copies prometheus.yml file to the working dir
Modifies configurations in Prometheus to leverage new MON exporter.
Modifies OSM Sample Dashboard at Grafana to point to new metric names.
Removes "Kafka Exporter" container (previous workaround to get metrics from bus)

Signed-off-by: lavado <glavado@whitestack.com>
Change-Id: I15451f717d9ee1cfbdee266a84ed29398360ed94