Don't show keyboard shortcuts with redbox on device

Summary:
Unless there is some really fancy way to make pressing the keyboard shortcuts like cmd+r from your dev machine and have it reload on your device like you can in the simulator, we probably shouldn't display these when running on device.

![img_4679](https://cloud.githubusercontent.com/assets/90494/17316248/331d890a-5827-11e6-9796-0f2bf24315d7.PNG)

<img width="487" alt="screen shot 2016-08-01 at 8 29 41 pm" src="https://cloud.githubusercontent.com/assets/90494/17316250/3b174e5c-5827-11e6-8337-ac0c01843fae.png">

![img_4677](https://cloud.githubusercontent.com/assets/90494/17316257/47aebcd6-5827-11e6-8a16-b128275f73e8.JPG)
Closes https://github.com/facebook/react-native/pull/9154

Differential Revision: D3663618

Pulled By: javache

fbshipit-source-id: 22d85d65702fa8d99788b79d04136c36da0d5b66