Added gerrit custom network to docker compose file model

Change-Id: I52c67cfa6cdcaf9437ca92e0c9795f767c616d8e
diff --git a/docker/client/compose/service/gerrit.yml b/docker/client/compose/service/gerrit.yml
index 183f57d..eeb126e 100644
--- a/docker/client/compose/service/gerrit.yml
+++ b/docker/client/compose/service/gerrit.yml
@@ -65,6 +65,12 @@
                 - 13306:3306
               volumes:
                 - /srv/volumes/mysql:/var/lib/mysql
+          network:
+            default:
+              ipam:
+                driver: default
+                config:
+                  - subnet: 172.30.0.0/24
   linux:
     system:
       directory: