change Dockerfile used for devops-stages to ubuntu 18.04

Change-Id: I32393a8056c5b69f07f058425ed5dcd6747ef2ce
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>
diff --git a/Dockerfile b/Dockerfile
index b0e81bb..79c1a50 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -18,7 +18,7 @@
 # Use Dockerfile.local for running osm/LCM in a docker container from source
 
 
-FROM ubuntu:16.04
+FROM ubuntu:18.04
 
 RUN apt-get update && \ 
     DEBIAN_FRONTEND=noninteractive apt-get --yes install git tox make debhelper wget \