Should fix a conflict between acra and sample

I just found out that the app crashes when we use ACRA and no sample in the same project. Indeed, at runtime, ACRA is looking for a class named MyAppApplication (*example in tests), but this class does not exist since we deactivated sample generation. Therefore, it leads the app to crash at runtime.

I guess the best way to solve this bug is to generate this class in any case. That's what this commit does.