Add Docker build job for Jenkins 2.70

Change-Id: I37de529bc4ef066ebc1044bf90afcadc4cc70c80
diff --git a/jenkins/client/job/docker/init.yml b/jenkins/client/job/docker/init.yml
index 1a2e4d9..1da507c 100644
--- a/jenkins/client/job/docker/init.yml
+++ b/jenkins/client/job/docker/init.yml
@@ -26,6 +26,10 @@
               branch: "2.52"
               tags: "2.52 latest"
               dockerfile: "Dockerfile"
+            - name: jenkins
+              branch: "2.70"
+              tags: "2.70 latest"
+              dockerfile: "Dockerfile"
             - name: phpldapadmin
               branch: "master"
               tags: "latest"