Replace org.reactjs.native.example

[davesag]

Various bits of the app refer to org.reactjs.native.example and I need to work out how to remove that. My first attempt at doing so wound up with the app breaking, so it's not as easy as just deleting it.

Ref https://stackoverflow.com/questions/36119754/how-to-change-the-bundle-identifier-within-react-native (though take all the advice in there with several grains of salt)