Use vagrant to bootstrap the app

This pull request does a few things related to making it easy to bootstrap the application.

1. Uses Vagrant and a Vagrantfile to bootstrap the application for new developers.
2. Upgrades to `ruby 2.1.0`
3. Installs `dotenv-rails` to handle configuration variables
4. Installs `foreman` to specify processes that should run on heroku (and for a convenient upstart script -- used by Vagrant)
5. Ignores the `database.yml` and includes a more standard example file (`database.yml.example`)