feature/vagrant

Adds Vagrantfile and puppet manifests so that a user can easily setup a development environment with a running django server and all the necessary dependencies for both the system and application. Ideally, the user can do the following:

```sh
git clone https://github.com/Harvard-ATG/HarvardCards.git
cd HarvardCards
vagrant up
```

And then they will have a running server on `http://localhost:8080/`. If any changes are made to the `requirements.txt` or puppet manifest `manifests/site.pp`, all they need to do is a `vagrant provision` to get the server to update itself.

Note: this was adapted from [django-vagrant](https://github.com/Harvard-ATG/django-vagrant).

@jazahn can you review?