Write a script to update slackmojis.com emojis

[flamableconcrete]

https://slackmojis.com gets updated with new emojis every so often. We should keep up to date with it! But there are so many, and life is so hard! Good thing they have https://slackmojis.com/emojis.json for developers to work with. A script should be written to parse it and automatically put it in an emojipack format.