Image Modal CMS HTML Block subtype

- Added YAML file for the HTML template code for the modal to work
- Added CSS and JS code for modal to look and function properly
- Updated code to take comments into account.
- Simplified HTML template and expanded JS to set up image modal on load.
- Added preliminary drag script.
- Converted jQuery UI draggable to Draggabilly

@singingwolfboy, @frrrances - here's the image modal branch! with Draggabilly and everything!