Revert "Add rails-ujs"

This reverts commit b846df30f9.

Gemfile

@@ -88,7 +88,6 @@ gem 'formtastic-bootstrap'
 # as the JavaScript library
 gem 'jquery-rails'
 gem 'jquery-ui-rails', '~> 4.2.1'
-gem 'rails-ujs'
 
 # for languages validation
 gem 'iso-639'

Gemfile.lock

@@ -430,8 +430,6 @@ GEM
     rails-i18n (5.0.4)
       i18n (~> 0.7)
       railties (~> 5.0)
-    rails-ujs (0.1.0)
-      railties (>= 3.1)
     rails_12factor (0.0.3)
       rails_serve_static_assets
       rails_stdout_logging
@@ -699,7 +697,6 @@ DEPENDENCIES
   rails-assets-waypoints!
   rails-controller-testing
   rails-i18n (~> 5.0.0)
-  rails-ujs
   rails_12factor
   rdoc-generator-fivefish
   recaptcha
@@ -737,4 +734,4 @@ RUBY VERSION
    ruby 2.5.0p0
 
 BUNDLED WITH
-   1.17.3
+   1.17.1

app/assets/javascripts/application.js

@@ -11,7 +11,7 @@
 // GO AFTER THE REQUIRES BELOW.
 //
 //= require jquery
-//= require rails-ujs
+//= require jquery_ujs
 //= require jquery.mobile.custom.min
 //= require jquery.ui.draggable
 //= require jquery.ui.droppable