Added a version flag to print the version of cAdvisor per google#329.

cadvisor.go

@@ -40,11 +40,17 @@ var argPort = flag.Int("port", 8080, "port to listen")
 var maxProcs = flag.Int("max_procs", 0, "max number of CPUs that can be used simultaneously. Less than 1 for default (number of cores).")
 
 var argDbDriver = flag.String("storage_driver", "", "storage driver to use. Empty means none. Options are: <empty> (default), bigquery, and influxdb")
+var versionFlag = flag.Bool("version", false, "print cAdvisor version")
 
 func main() {
 	defer glog.Flush()
 	flag.Parse()
 
+	if *versionFlag {
+		fmt.Printf("cAdvisor version %s\n", info.VERSION)
+		os.Exit(0)
+	}
+
 	setMaxProcs()
 
 	storageDriver, err := NewStorageDriver(*argDbDriver)