Added update notifier.

It will be used to notify when there is a new stf release.

lib/cli.js

@@ -4,6 +4,7 @@ var os = require('os')
 var program = require('commander')
 var Promise = require('bluebird')
 var ip = require('my-local-ip')
+var updateNotifier = require('update-notifier')
 
 var pkg = require('../package')
 var cliutil = require('./util/cliutil')
@@ -14,6 +15,13 @@ Promise.longStackTraces()
 program
   .version(pkg.version)
 
+var notifier = updateNotifier({
+  packageName: pkg.name,
+  packageVersion: pkg.version
+})
+
+notifier.notify()
+
 program
   .command('provider [serial..]')
   .description('start provider')