#94 Automate naming of the virtual machine

This pull request refactors the Rakefile to automatically name the machine based on the standards that we use on downloads.puppetlabs.com. This is a precursor  to some vagrant stuff that I want to work on but should also simplify the process for builders like @casharma who have to manually rename these values. It was tested with `Centos` and the `rake everything` task. The debian URL in the file looks out of date so I did not prioritize testing on that. This also bumps the hardcoded version of PE to 3.0.0.