Introduce a Vagrantfile and provision with WSU Web Serverbase

[WSU Web Serverbase](https://github.com/washingtonstateuniversity/wsu-web-serverbase) contains all of the provisioning we need for production and development environments.

WSUWP Platform should include a Vagrantfile that uses `vagrant up` to:

* [ ] Retrieve the latest provisioning from WSU Web Serverbase
* [ ] Launch Salt with a specific minion configuration
* [ ] Map the current working directory to `/srv/www/` inside the VM
* [ ] Provide hosts configuration necessary for access to desired sites.

This eliminates the need for the WSUWP Environment repository beyond historic documentation.