Add draggabilly

Draggabilly is Javascript library to make elements draggable.
The minified source draggabilly.pkgd.min.js is downloaded from
http://draggabilly.desandro.com/

Author: David DeSandro
License: MIT
Repository: https://github.com/desandro/draggabilly
Merge pull request #1270 from danmasera/drag

Add draggabilly