Added backup locale lists to locale not available page

app/views/application/locale_not_available.html.haml

@@ -1,9 +1,9 @@
-= render :partial => 'application/header', :locals => {:image_file => 'runes.jpg'}
+= render partial: 'application/header', locals: {image_file: 'runes.jpg'}
 = row do
   = columns(medium: 12) do
     %p= _'error.locale_not_available.description', :p, @main_title_vars
     %ul.locales
-			- @alt_lang_urls.each do |locale, url|
+      - (@alt_lang_urls || I18n.backend.enabled_locales.sort || [:en]).each do |locale, url|
         %li
           - locale_translation = language_name(locale, true)
           %a.button{href: url, lang: locale}