Update to Play 2.4.x with InjectedRoutesGenerator

[mantsak]

Fantastic webinar and exciting technology!

I tried to update the project to Play 2.4.x at

https://github.com/mantsak/ping-play/tree/2.4.x

My knowledge is not that deep to get the application running. I changed the Controller classes from objectto class, but there is still some coding left. It would be great if this repositary can be updated. If you implement the changes in your code, I will delete my fork. Or update my fork with a pull request to keep your version according to your presentation.

[brikis98]

I just upgraded this repo to Play 2.4, but there are a few issues:

1. The Java examples no longer work, possibly due to a bug or design issue in Play 2.4 with compile-time dependency injection. I've filed #13 to track this.
2. The Docker image no longer builds due to a change in the progrium/busybox image. I've filed #14 to track this.

Talk about yak shaving :)