Fixing nginx docker image in Jenkinsfile

Change-Id: I76a0c12fab00c6a25db160d9c210757f1e0de220
diff --git a/Jenkinsfile b/Jenkinsfile
index d53ff3f..d11c4c5 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -26,6 +26,8 @@
                 sh 'npm test'
 
                 stage 'Build GUI docker container'
+                sh 'docker pull nginx'
+                sh 'docker tag nginx nginx:candidate'
                 sh 'docker build --no-cache -t xosproject/xos-gui .'
                 sh 'docker run -p 4000:4000 --net=host --name xos-gui -d xosproject/xos-gui'
 
@@ -40,7 +42,7 @@
                 stage 'Clean'
                 sh 'docker stop xos-gui'
                 sh 'docker rm xos-gui'
-                sh 'docker rmi -f xosproject/xos-gui'
+                sh 'docker rmi -f $(docker images -aq)'
             }
             echo "RESULT: ${currentBuild.result}"
        }