Summary:
Basic template using 'react-navigation' to make it easy to get started.
Not duplicating all the files in `android` and `ios` folders. These will be taken from the `HelloWorld` template. Let's not duplicate all of these files (it's a lot and they are large, especially the Xcode projects).
**Test plan (required)**
The app works locally. This PR is just a preparation for a next PR that will add support for 'react-native init --template Navigation'. Will have a proper test plan there.
Closes https://github.com/facebook/react-native/pull/12153
Differential Revision: D4494776
Pulled By: mkonicek
fbshipit-source-id: b43eafd7a1424477f9493a3eb4083ba4dd3d3846
Martin Konicek