include uglifier for production

Author: nicolasfranck

Gemfile

@@ -349,3 +349,5 @@ group :development do
   # TomDoc for YARD (http://rubyworks.github.com/yard-tomdoc)
   gem "yard-tomdoc"
 end
+
+gem "uglifier"

Gemfile.lock

@@ -436,6 +436,8 @@ GEM
     turbolinks-source (5.2.0)
     tzinfo (1.2.7)
       thread_safe (~> 0.1)
+    uglifier (4.2.0)
+      execjs (>= 0.3.0, < 3)
     unicode-display_width (1.7.0)
     uniform_notifier (1.13.0)
     warden (1.2.8)
@@ -542,6 +544,7 @@ DEPENDENCIES
   text
   translation
   turbolinks
+  uglifier
   web-console
   webdrivers
   webmock