use a script to generate stackbrew versions
diff --git a/update.sh b/update.sh
new file mode 100755
index 0000000..a0d7f15
--- /dev/null
+++ b/update.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+set -e
+
+versions=( "$@" )
+if [ ${#versions[@]} -eq 0 ]; then
+	versions=( */ )
+fi
+versions=( "${versions[@]%/}" )
+
+for version in "${versions[@]}"; do
+	rm -rf "$version"/*
+	cp Dockerfile.template jenkins.sh plugins.sh init.groovy "$version/"
+	mv "$version/Dockerfile.template" "$version/Dockerfile"
+	sed -i "" 's/%%JENKINS_VERSION%%/'$version'/g; s/%%JENKINS_VERSION%%/'$version'/g' "$version/Dockerfile"
+done
+