Update Make recipe for deploy

GitHub.com automatically generates organization pages based on the
contents of the `master` branch, so the deployment script should push
compiled content to that branch instead.

> # User & Organization Pages
>
> **User & Organization Pages** live in a special repository dedicated
> to GitHub Pages files. You will need to name this repository with the
> account name, e.g. atmos/atmos.github.io.
>
> - You must use the `username/username.github.io` naming scheme.
> - Content from the `master` branch will be used to build and publish
>   your GitHub Pages site.

Source:
https://help.github.com/articles/user-organization-and-project-pages
Integrate Vagrant
Deploy site