Make react-native run-[android/ios] and react-native start and react-native link work as expected in CRNA

[brentvatne]

Description

It's kind of silly that we have two approaches for doing the same thing depending on whether you're using an app bootstrapped with react-native-cli or Create React Native App.

Expected Behavior

react-native-cli commands should delegate to the CRNA equivalent when they are used in the CRNA context

Observed Behavior

They start the react-native packager without using Create React Native App: facebook/react-native#14828

[Hum4n01d]

+1

[brentvatne]

Also, react-native-cli should throw an informative error when you try to react-native link on a CRNA project

[fson]

I've created a pull request in the react-native repository with this improvement: facebook/react-native#15139.