adding support for Vagrant

This pull request adds:

- a Vagrantfile for a Debian 7 VM, already with www ports and source folder mapped
- a bootstrap/installation script for said VM, that will run automatically upon `vagrant up'

To experiment with this, install [vagrant](http://www.vagrantup.com/), and issue a `vagrant up' command from inside your local working copy. This will download the debian box image, spin up the VM and provision the dependencies.

This setup is recommended solely for development purposes.

For more information about vagrant, please refer to the project's website.