specify docker auth parameters

Author: rbygrave

pom.xml

@@ -354,6 +354,10 @@
               <to>
                 <image>docker.io/rbygrave/ebean-insight</image>
                 <tags>${project.version}</tags>
+                <auth>
+                  <username>${env.DOCKER_USERNAME}</username>
+                  <password>${env.DOCKER_PASSWORD}</password>
+                </auth>
               </to>
               <container>
                 <ports>8081</ports>