Add Vagrantfile for module testing

To find out whether the `init.d` script provider works as intended on Ubuntu:

    vagrant up

This'll come in especially handy when testing multiple instance support: just extend the `vagrant.pp` file to add both log-gathering and log-indexing instances. I'd stick with the embedded ElasticSearch. 

I've tested adding [thomasvandoren/redis] to the `vagrant-prereqs.pp` file: it works fine.

     vpupmod {
      'puppetlabs/stdlib':;
      'thomasvandoren/redis':;
    }

[thomasvandoren/redis]: http://forge.puppetlabs.com/thomasvandoren/redis