Add --version flag.

pkg/version/version.go

@@ -0,0 +1,23 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package version
+
+import "fmt"
+
+// version defines the version
+var version string = "UNKNOWN"
+
+func PrintVersion() {
+	fmt.Println(version)
+}