don't make assumptions about command line arguments invoking webpack config

config/webpack.config.js

@@ -11,7 +11,7 @@ var WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeMod
 
 var ROOT_PATH = path.resolve(__dirname, '..');
 var IS_PRODUCTION = process.env.NODE_ENV === 'production';
-var IS_DEV_SERVER = process.argv[1].indexOf('webpack-dev-server') !== -1;
+var IS_DEV_SERVER = process.argv.join(' ').indexOf('webpack-dev-server') !== -1;
 var DEV_SERVER_HOST = process.env.DEV_SERVER_HOST || 'localhost';
 var DEV_SERVER_PORT = parseInt(process.env.DEV_SERVER_PORT, 10) || 3808;
 var DEV_SERVER_LIVERELOAD = process.env.DEV_SERVER_LIVERELOAD !== 'false';