Wrap development and build workflow in Vagrant and Make

In order make the process of developing against or building this project easier, this pull request wraps everything inside of a Vagrant project. In addition to Vagrant, Ansible is used to provision the Vagrant virtual
machine.

Please see `README` changes for revised workflow details.

Resolves #23.
Is this a good time to switch from `github.com/azavea/ecobenefits` to `github.com/OpenTreeMap/ecobenefits`?