Boilerplate branch for developer projects

[jasonnrosa]

Types of change

• [ ] Bug fix (change which fixes an issue)
• [ ] Enhancement (change which improves upon an existing feature)
• [X] New feature (change which adds new functionality)

Description

Creating a branch of the boilerplate that leverages the .hubl file extension for HTML, CSS, and JS files so that it works properly with developer projects. This branch will remain as a draft until further notice and shouldn't be used outside of developer projects.

Relevant links

Fixes #392

Checklist

• [X] I have read the CONTRIBUTING document.
• [X] My code follows the style guide requirements.
• [X] I have thoroughly tested my change.

People to notify CC: @gcorne @brandenrodgers @TheWebTech and @ajlaporte