Bump emoji requirement to Unicode 9

app/assets/javascripts/components/emoji.jsx

@@ -9,7 +9,7 @@ let emoji_version = detectVersion();
 
 export default function emojify(text) {
   // Browser too old to support native emoji
-  if (emoji_version < 6.1) {
+  if (emoji_version < 9.0) {
     return emojione.toImage(text);
   // Convert short codes into native emoji
   } else {