Add emoji menu

[amgassert]

Estimated Time: 32 hours

Additional Information

• The emoji menu button should be placed under the insert item menu (designated by the '+' button) at the left edge of the chat text box
• Upon clicking the emoji menu button, the emoji menu should replace the insert item menu
• Clicking on an emoji should place that emoji's code in the chat text box
• A search bar should be at the top of the emoji menu
• Searching for an emoji code shows all emoji with matching codes
• Hovering over an emoji in the menu should show its code in the search bar.

Test Plan

• TBD

Related Issue: #121 Blocked by: #121

[NullVoxPopuli]

list of emojis / import path: https://raw.githubusercontent.com/omnidan/node-emoji/master/lib/emoji.json