Change JDK container for Docker build

- the image we were using is no longer supported
- we are now using an OpenJDK 8 image for docker builds
- removed Jono as author and put in myself

Change-Id: I7a4d607da32d1da4449e7421b6df1d23ea9eb9f4
diff --git a/Dockerfile b/Dockerfile
index a4709b8..7270381 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 # First stage is the build environment
-FROM sgrio/java-oracle:jdk_8 as builder
-MAINTAINER Jonathan Hart <jono@opennetworking.org>
+FROM picoded/ubuntu-openjdk-8-jdk as builder
+MAINTAINER Ray Milkey <ray@opennetworking.org>
 
 # Set the environment variables
 ENV HOME /root