Bug 562908 - Populate the JustJ Git clones with initial content

Ensure that artifacts are packed and signed.
diff --git a/releng/org.eclipse.justj.tools.releng/Jenkinsfile b/releng/org.eclipse.justj.tools.releng/Jenkinsfile
index 8dfcf1d..60c35d1 100644
--- a/releng/org.eclipse.justj.tools.releng/Jenkinsfile
+++ b/releng/org.eclipse.justj.tools.releng/Jenkinsfile
@@ -89,7 +89,7 @@
               if [[ $PROMOTE == false ]]; then
                 promotion_argument='-Dorg.eclipse.justj.p2.manager.args='
               fi
-              mvn $promotion_argument -Dorg.eclipse.justj.p2.manager.relative=$PUBLISH_LOCATION -Dbuild.type=$BUILD_TYPE -Dgit.commit=$GIT_COMMIT -Dbuild.id=$BUILD_NUMBER clean verify
+              mvn $promotion_argument -DPACK_AND_SIGN=true -Dorg.eclipse.justj.p2.manager.relative=$PUBLISH_LOCATION -Dbuild.type=$BUILD_TYPE -Dgit.commit=$GIT_COMMIT -Dbuild.id=$BUILD_NUMBER clean verify
               '''
           }
         }