Adds use of uri in connection to MongoDB instead of host and port

MON now uses a mongodb uri to connect to the database. This allows to use uris
that define either a single node db or a replica set, allowing for HA
scenarios.

Signed-off-by: Benjamin Diaz <bdiaz@whitestack.com>
diff --git a/docker/Dockerfile b/docker/Dockerfile
index ec70d87..f843908 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -37,7 +37,7 @@
 RUN pip3 install /mon
 
 ENV BROKER_URI kafka:9092
-ENV MONGO_URI mongo:27017
+ENV MONGO_URI mongodb://mongo:27017
 ENV DATABASE sqlite:///mon_sqlite.db
 ENV OS_NOTIFIER_URI localhost:8662
 ENV OS_DEFAULT_GRANULARITY 300