Add --version to local-cli/cli.js

Summary:
[Buck](https://buckbuild.com) has a concept of a versioned tool.  In order to
properly use RN with Buck, the `cli.js` script should return the proper version
when passed `--version`.

Reviewed By: astreet

Differential Revision: D3197207

fb-gh-sync-id: 12ea35587cf492eb89d7dd102e93bdd26bc813c0
fbshipit-source-id: 12ea35587cf492eb89d7dd102e93bdd26bc813c0

local-cli/cli.js

@@ -30,6 +30,7 @@ var TerminalAdapter = require('yeoman-environment/lib/adapter.js');
 var yeoman = require('yeoman-environment');
 var unbundle = require('./bundle/unbundle');
 var upgrade = require('./upgrade/upgrade');
+var version = require('./version/version');
 
 var fs = require('fs');
 var gracefulFs = require('graceful-fs');
@@ -56,6 +57,7 @@ Object.keys(documentedCommands).forEach(function(command) {
 });
 
 var undocumentedCommands = {
+  '--version': [version, ''],
   'init': [printInitWarning, ''],
 };
 

local-cli/version/version.js

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+var pkg = require('../../package');
+var Promise = require('promise');
+
+/**
+ * Prints the version of react-native and exits.
+ */
+function version(argv, config) {
+  console.log(pkg.version);
+  return Promise.resolve();
+}
+
+module.exports = version;