Gem gon added. It produces server-side variable values in javascript

Gemfile

@@ -115,6 +115,7 @@ group :assets do
   gem 'bootstrap-sass',   "2.2.1.1"
   gem "font-awesome-sass-rails", "~> 3.0.0"
   gem "gemoji", "~> 1.2.1", require: 'emoji/railtie'
+  gem "gon"
 end
 group :development do

Gemfile.lock

@@ -184,6 +184,9 @@ GEM
       pyu-ruby-sasl (~> 0.0.3.1)
       rubyntlm (~> 0.1.1)
     gitlab_yaml_db (1.0.0)
+    gon (4.0.2)
+      actionpack (>= 2.3.0)
+      json
     grape (0.2.2)
       activesupport
       hashie (~> 1.2)
@@ -483,6 +486,7 @@ DEPENDENCIES
   gitlab_meta (= 5.0)
   gitlab_omniauth-ldap (= 1.0.2)
   gitlab_yaml_db (= 1.0.0)
+  gon
   grack!
   grape (~> 0.2.1)
   grit!

app/views/layouts/_head.html.haml

@@ -7,6 +7,7 @@
   = stylesheet_link_tag    "application"
   = javascript_include_tag "application"
   = csrf_meta_tags
+  = include_gon
   -# Atom feed
   - if current_user