Update Emoji asset path

Now that we're serving assets directly from the Gemojione gem's path,
the images are not in an `emoji/` sub-folder.

app/controllers/projects_controller.rb

@@ -236,7 +236,7 @@ class ProjectsController < ApplicationController
       Emoji.emojis.map do |name, emoji|
         {
           name: name,
-          path: view_context.image_url("emoji/#{emoji["unicode"]}.png")
+          path: view_context.image_url("#{emoji["unicode"]}.png")
         }
       end
     end

config/application.rb

@@ -43,8 +43,8 @@ module Gitlab
 
     # Enable the asset pipeline
     config.assets.enabled = true
-    config.assets.paths << Emoji.images_path
-    config.assets.precompile << "emoji/*.png"
+    config.assets.paths << Gemojione.index.images_path
+    config.assets.precompile << "*.png"
     config.assets.precompile << "print.css"
 
     # Version of your assets, change this if you want to expire all your assets

lib/banzai/filter/emoji_filter.rb

@@ -45,7 +45,8 @@ module Banzai
       private
 
       def emoji_url(name)
-        emoji_path = "emoji/#{emoji_filename(name)}"
+        emoji_path = emoji_filename(name)
+
         if context[:asset_host]
           # Asset host is specified.
           url_to_image(emoji_path)