Replace singleton pattern with dependency injection

[hadiidbouk]

Is there any chance to drop the singleton pattern and use dependency injection ? Or at least making the code flexible if someone want to use DI with a third library like Dagger

[Steppschuh]

For simplicity, I wouldn't force developers to use dependency injection. Same reason why we don't rely on RxJava in this library, although we use it in our internal projects.

If you can implement optional support for Dagger while maintaining the current pattern, feel free to submit a PR.

[hadiidbouk]

I will see, thank you