Use twemoji so emoji work for all

Author: Flet

lib/rich-message.js

@@ -6,6 +6,7 @@ var ghlink = require('ghlink')
 var higlight = require('highlight.js')
 var htmlToVDom = require('html-to-vdom')
 var MarkdownIt = require('markdown-it')
+var twemoji = require('twemoji')
 var util = require('./util.js')
 var VNode = require('virtual-dom/vnode/vnode')
 var VText = require('virtual-dom/vnode/vtext')
@@ -27,6 +28,10 @@ var md = new MarkdownIt({
   }
 }).use(emoji)
 
+md.renderer.rules.emoji = function (token, index) {
+  return twemoji.parse(token[index].content)
+}
+
 var convertHTML = htmlToVDom({
   VNode: VNode,
   VText: VText