Add ability to silence packager logs to stdout

Summary:We use a few different modules to output logs to stdout when building a bundle with the packager:
- ##js/react-native-github/packager/react-packager/src/Activity/index.js##
- ##js/react-native-github/local-cli/util/log.js##
- ##https://www.npmjs.com/package/progress##

This diff also adds a ##silent## option to the packager ##Server##, which, when ##true##, will not create a ##progress## instance for the transformer.

Reviewed By: martinbigio

Differential Revision: D3048739

fb-gh-sync-id: a4c6caf36f5127946593f4a0a349fa145ad0d4e6
shipit-source-id: a4c6caf36f5127946593f4a0a349fa145ad0d4e6

react-packager/src/Bundler/index.js

@@ -81,6 +81,10 @@ const validateOpts = declareOpts({
     type: 'number',
     required: false,
   },
+  silent: {
+    type: 'boolean',
+    default: false,
+  },
 });
 
 class Bundler {
@@ -352,8 +356,8 @@ class Bundler {
     const modulesByName = Object.create(null);
 
     if (!resolutionResponse) {
-      let onProgess;
-      if (process.stdout.isTTY) {
+      let onProgess = noop;
+      if (process.stdout.isTTY && !this._opts.silent) {
         const bar = new ProgressBar(
           'transformed :current/:total (:percent)',
           {complete: '=', incomplete: ' ', width: 40, total: 1},

react-packager/src/Server/index.js

@@ -73,6 +73,10 @@ const validateOpts = declareOpts({
     type: 'string',
     required: false,
   },
+  silent: {
+    type: 'boolean',
+    default: false,
+  },
 });
 
 const bundleOpts = declareOpts({