Revise code, update project structure/configs/gradle files

[livotovlabs]

Revise code, update project structure/configs/gradle files

[mezpahlan]

Hi @livotov in a previous PR I bumped the Android Gradle Plugin version to 4.2.0-alpha16 and now looking back I don't think I should have done that without discussing with you first. The reason I did that is because I use the canary build of Android Studio at home and it suggested that I update the plugin to the canary version.

However I realise two things:

1. The canary version updates all the time meaning I'm having to update the version in each PR I open. Often this change is unrelated to the change in the PR so is a distraction.
2. This forces other contributors (and yourself) to use the canary version of Android Studio which unless that is also your project decision is probably not something I should have decided on my own.

The good news is that if I set the Android Gradle Plugin back to the latest stable, my canary version of Android Studio no longer complains. This also means that everyone else wanting to contribute can continue to use their preferred version of Android Studio knowing that the project dependencies are stable.

Hopefully that makes sense. I'll raise a PR shortly to lower it.

[livotov]

Thanks, looks good!