Lintian integration tests

I was having some issues with `lintian` and packages generated by `fpm`. Specifically after [this](https://github.com/jordansissel/fpm/commit/0e78dc1b199c7b99bc53928dadcd4f7ffdc8c6df) commit.

I think I've fixed this issue as well as adding some integration tests (hopefully might be useful to expand on these tests to make sure `fpm` is doing sane things).

I've also made some somewhat opinionated changes that I hope you're okay with:
- Changed the `box_url`s in the `Vagrantfile` to use boxes that exist publicly (built and maintained by Puppet Labs).
- Removed the check for `/EMPTY` in the Puppet manifest—this really shouldn't be required and indicates something wrong with the box.

Hope you like the changes! :-)