remove rack cache, it has been causing trouble

instead implement an aggressive anonymous cache that is stored in redis
this cache is sitting in the front of the middleware stack enabled only in production
TODO: expire it more intelligently when stuff is created

app/controllers/application_controller.rb

@@ -155,35 +155,15 @@ class ApplicationController < ActionController::Base
   end
 
   def can_cache_content?
-    # Don't cache unless we're in production mode
-    return false unless Rails.env.production? || Rails.env == "profile"
-
-    # Don't cache logged in users
-    return false if current_user.present?
-
-    true
+    !current_user.present?
   end
 
   # Our custom cache method
   def discourse_expires_in(time_length)
     return unless can_cache_content?
-    expires_in time_length, public: true
+    Middleware::AnonymousCache.anon_cache(request.env, 1.minute)
   end
 
-  # Helper method - if no logged in user (anonymous), use Rails' conditional GET
-  # support. Should be very fast behind a cache.
-  def anonymous_etag(*args)
-    if can_cache_content?
-      yield if stale?(*args)
-
-      # Add a one minute expiry
-      expires_in 1.minute, public: true
-    else
-      yield
-    end
-  end
-
-
   def fetch_user_from_params
     username_lower = params[:username].downcase
     username_lower.gsub!(/\.json$/, '')