Remove FragmentLocalization and localized_cache helper

We replace the `localized_cache` helper with just simple keys provided
to the `cache` helper, with `locale=#{I18n.locale}` inlined. End of an
era!

app/controllers/application_controller.rb

@@ -2,8 +2,6 @@ require 'async'
 require 'async/container'
 
 class ApplicationController < ActionController::Base
-  include FragmentLocalization
-  
   protect_from_forgery
 
   helper_method :current_user, :user_signed_in?

app/helpers/application_helper.rb

@@ -1,6 +1,4 @@
 module ApplicationHelper
-  include FragmentLocalization
-
   def absolute_url(path_or_url)
     if path_or_url.include?('://') # already an absolute URL
       path_or_url
@@ -166,13 +164,6 @@ module ApplicationHelper
     options
   end
 
-  def localized_cache(key={}, &block)
-    localized_key = localize_fragment_key(key, locale)
-    # TODO: The digest feature is handy, but it's not compatible with how we
-    # check for fragments existence in the controller, so skip it for now.
-    cache(localized_key, skip_digest: true, &block)
-  end
-
   def auth_user_sign_in_path_with_return_to
     new_auth_user_session_path :return_to => request.fullpath
   end

app/views/items/index.html.haml

@@ -31,7 +31,7 @@
       %h2= t '.newest_items.header'
       = render @newest_items
 
-  - localized_cache :action_suffix => 'species_search_links' do
+  - cache "items/index species_search_links locale=#{I18n.locale}" do
     #species-search-links
       %h2= t '.species_search.header'
       = standard_species_search_links

app/views/outfits/new.html.haml

@@ -90,7 +90,7 @@
     %h3= t '.newest_items.unmodeled.header'
     %ul#newest-unmodeled-items
       - @newest_unmodeled_items.each do |item|
-        - localized_cache "items/#{item.id} modeling_progress updated_at=#{item.updated_at.to_i}" do
+        - cache "items/#{item.id} modeling_progress locale=#{I18n.locale} updated_at=#{item.updated_at.to_i}" do
           %li{'data-item-id' => item.id}
             = link_to image_tag(item.thumbnail_url), item, :class => 'image-link'
             = link_to item, :class => 'header' do

lib/fragment_localization.rb

@@ -1,11 +0,0 @@
-module FragmentLocalization
-  def localize_fragment_key(key, locale)
-    if key.is_a?(Hash)
-      {:locale => locale}.merge(key)
-    elsif key.is_a?(String)
-      "#{key} #{locale}"
-    else
-      raise TypeError, "unexpected fragment key type: #{key.class}"
-    end
-  end
-end