Ability to add/display emojis within posts and threads

[lonnieezell]

We should support the ability to add emojis to our posts and threads. An admin should be able to add new ones, or remove old ones.

I really like Slack's implantation here, where you can type a text short cut, like :joy: and it will be replace with the appropriate icon. This would be a fairly simple system to implement to, I would think.

At one point, I'm pretty sure one of the Slack founders had their emoji library available open-source. Not sure if it's still around or not.