Integrate Deploy Preview to be able to check that PRs don't break everything

[calavera]

- Do you want to request a feature or report a bug?

This is a feature.

- What is the current behavior?

There is no way to know if new changes break the template.

- What is the expected behavior?

We should have Netlify building deploy previews of this repository and notifying pull requests so we can verify that new changes don't break the template.