Replaces direct use of aiokafka with osm_common message bus in agent and
lcmclient

Changes config handling to comply with the way it is handled in other modules,
by using a config file and overriding it with env vars.

Adds unit tests for message_bus_client.

Mon client remains using aiokafka directly, as there is no support yet for
auto_offset_reset configuration in osm_common.

Change-Id: I99615287cc934ce310105e86544a6bfe26bc0673
Signed-off-by: Benjamin Diaz <bdiaz@whitestack.com>
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 91bc5f6..7f57036 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -45,7 +45,6 @@
 
 ENV OSMPOL_SQL_DATABASE_URI sqlite:///policy_module.db
 
-ENV OSMPOL_LOG_LEVEL INFO
-ENV OSMPOL_KAFKA_LOG_LEVEL WARN
+ENV OSMPOL_GLOBAL_LOG_LEVEL INFO
 
 CMD osm-policy-agent