First refactoring to provide multiple debian packaging strategies

This is the first refactoring step to provide an additional java-based debian packaging implementation.
Does this look okay from the coding side? @jsuereth , @kardapoltsev , @aparkinson ?

I basically introduced two new task `debianJDebPackaging` and `debianNativePackaging`.
You set the packaging strategy with `packageBin in Debian <<= debianJDebPackaging in Debian`.
Ah nice, I had been watching this guy.