Make it work with check_mode

[diraol]

Ok, even with the small fix I proposed in #38, it was still not working in check_mode (because a bunch of reasons).

So this PR aims to make it work also with in --check (check mode). I had to set a small "hack" to make it work because neither command not shell effectively run in check_mode, so we couldn't get the current version result from them (using dpkg shell command).