Don’t report failure to npm-start with arg support

Summary: This supports passing args to `npm start` as referenced in [this comment][comment] while still returning 0 on failure from an npm perspective.

This builds off the npm change in [this commit][commit] and discussed in this [PR].

[comment]: https://github.com/facebook/react-native/pull/2415#issuecomment-141309448
[commit]: 75df3b537a
[PR]: https://github.com/facebook/react-native/pull/2415
Closes https://github.com/facebook/react-native/pull/3002

Reviewed By: svcscm

Differential Revision: D2647258

Pulled By: spicyj

fb-gh-sync-id: 2385254d23a37a99a53f53308e4688bc1fc3124e

package.json

@@ -47,7 +47,7 @@
   "scripts": {
     "test": "NODE_ENV=test jest",
     "lint": "eslint Examples/ Libraries/",
-    "start": "./packager/packager.sh || true"
+    "start": "/usr/bin/env bash -c './packager/packager.sh \"$@\" || true' --"
   },
   "bin": {
     "react-native": "local-cli/wrong-react-native.js"