Careful seeing it. I was trying to test GCM API, this was a fast code where I didn't want to evolute.
Some solutions adopted here are not great. Like project structure, there is bin, libs, etc, commited on repository. Another mistake is, there are some keys commited on repository, which is a rookie mistake. Today all keys are invalidated.
So don't use this code as guidelines.
But anyway, I want to keep it, just to see my own evolution.