Followup of #9568, some cleanup

Summary:
As mkonicek suggested in [#9568](https://github.com/facebook/react-native/pull/9568#issuecomment-267600043) I did some cleanup

**Test plan (required)**

Only one functional change:
> Run `react-native run-android --deviceId`

Before it was beginning to build the app and then failing because of the missing device "true" :-)
Now it's showing a message and stopping the build:
```
❯ react-native run-android --deviceId
Starting JS server...
Parameter missing (device id)
```
Closes https://github.com/facebook/react-native/pull/11703

Differential Revision: D4376615

Pulled By: ericvicenti

fbshipit-source-id: 3c6e0f12220ab22539c7bc3d390367e02c96728a