Precompile CKEditor dialog plugins

In some cases, in the production environment the dialogs for links,
images and tables didn't work, because these plugins were not
precompiled.

config/initializers/ckeditor.rb

@@ -8,5 +8,5 @@ Ckeditor.setup do |config|
   config.authorize_with :cancan
 
   config.assets_languages = Rails.application.config.i18n.available_locales.map{|l| l.to_s.downcase}
-  config.assets_plugins = %w[copyformatting tableselection scayt wsc]
+  config.assets_plugins = %w[copyformatting image link magicline scayt table tableselection wsc]
 end