add missing ActiveSupport::Notifications.subscribe calls (thanks @reprazent)

          subscriber = new

          subscriptions = [

            CacheReadSubscriber.new,

            CacheGenerateSubscriber.new,

            CacheFetchHitSubscriber.new,

            CacheWriteSubscriber.new,

            CacheDeleteSubscriber.new,

            ActiveSupport::Notifications.subscribe(CACHE_READ_TOPIC, CacheReadSubscriber.new),

            ActiveSupport::Notifications.subscribe(CACHE_GENERATE_TOPIC, CacheGenerateSubscriber.new),

            ActiveSupport::Notifications.subscribe(CACHE_FETCH_HIT_TOPIC, CacheFetchHitSubscriber.new),

            ActiveSupport::Notifications.subscribe(CACHE_WRITE_TOPIC, CacheWriteSubscriber.new),

            ActiveSupport::Notifications.subscribe(CACHE_DELETE_TOPIC, CacheDeleteSubscriber.new),

          ]

          create_unsubscriber subscriptions