Fix #4149, fix #1199 - Store emojis as unicode (#4189)

- Use unicode when selecting emoji through picker
- Convert shortcodes to unicode when storing text input server-side
- Do not convert shortcodes in JS anymore

Gemfile

@@ -28,6 +28,7 @@ gem 'devise', '~> 4.2'
 gem 'devise-two-factor', '~> 3.0'
 gem 'doorkeeper', '~> 4.2'
 gem 'fast_blank', '~> 1.0'
+gem 'gemoji', '~> 3.0'
 gem 'goldfinger', '~> 1.2'
 gem 'hiredis', '~> 0.6'
 gem 'redis-namespace', '~> 1.5'