Ignite: Suggest troubleshooting tips when missing environment prerequisites

[dabbott]

The first time I tried ignite new Project, my Android prerequisite was not found, which led to the Android build failing.

In my case, it came down to missing android in my PATH (when I installed RN ages ago, I don't think this wasn't needed), but I only figured that out by searching for similar git issues on this repo.

It would be super helpful to display suggestions to the user in the case of a missing prerequisite. For example, if Android is missing, some combination of these suggestions would be helpful:

• Unable to find 'android' in your PATH.
• Unable to find 'ANDROID_HOME' environment variable.
• Make sure you've followed the latest react-native setup instructions at https://facebook.github.io/react-native/docs/getting-started.html before using ignite.
• If you're only targeting iOS, you may continue now and set up Android another time. The Android files will all be generated, but the build will fail.

[GantMan]

/gif IT SHALL BE DONE!

[Danm72]

Bump, just installed it with $ANDROID_HOME in my path and still got the Missing android error.