Does not work in Internet Explorer (11)

[Mark-Hetherington]

It appears that Internet Explorer is not compatible with the gfycat.js embedding script. I'm currently getting an error in the developer console:
SCRIPT5009: 'Promise' is undefined
gfycat.js (16,9228)

According to caniuse.com (http://caniuse.com/#feat=promises) It looks like IE does not have Promise support, and thus a polyfill is required.

I see two ways forward - one is to document this requirement, the other is to include the polyfill in the gfycat.js script file.