Try to move upstream ejected HelloWorld template to a single index.js entry point

[anp]

The HelloWorld template project in react-native/local-cli currently assumes that there will be two entry points: index.ios.js and index.android.js. CRNA projects start with a single main.js (although this is fungible and could easily be called index.js), which breaks on iOS (haven't tested Android) once ejected to a regular RN project.

For now I'm implementing some dirty hacks around this, but would like to make the upstream template project(s) compatible with CRNA's eject in the near term. I think this will just require a PR that I don't have bandwidth to write and push through right now.

EDIT: this wouldn't just require unifying the files, it looks like test and example code (and maybe docs?) assume that these files will be separate.

[mkonicek]

I like main.js better than index.js actually! Index is so webby :)

But actually we're trying to bring RN and web development closer together, so let's keep index. Also people are kind of used to it by now.

[anp]

:D I should note that I moved the CRNA template to index.js to match up with the dirty hack I wrote for providing the HelloWorld template with index.(ios|android).js files. Can definitely change it back!

[mkonicek]

Cool I'll update the template.

[mkonicek]

index.js is good (edited my comment above) 👍

[anp]

@mkonicek does this seem like something likely to make it into 0.42?

[fson]

I'm working on a pull request to make this change to the HelloWorld template in react-native and all the tests and docs that refer to the old index.ios.js/index.android.js files.

[fson]

I've made the upstream changes here: facebook/react-native#15312.