replace Configuration with Cleaners, as the former is just a wrapper, now.

lib/database_cleaner/configuration.rb

@@ -1,9 +1,6 @@
 require 'database_cleaner/base'
-require 'database_cleaner/deprecation'
-require 'forwardable'
 
 module DatabaseCleaner
-
   class Cleaners < Hash
     def initialize hash={}
       super.replace(hash)
@@ -56,23 +53,4 @@ module DatabaseCleaner
       end)
     end
   end
-
-  class Configuration
-    def initialize
-      @cleaners ||= Cleaners.new
-    end
-
-    extend Forwardable
-    delegate [
-      :[],
-      :strategy=,
-      :orm=,
-      :start,
-      :clean,
-      :cleaning,
-      :clean_with,
-    ] => :cleaners
-
-    attr_accessor :cleaners
-  end
 end

lib/database_cleaner/core.rb

@@ -8,8 +8,6 @@ module DatabaseCleaner
     extend Forwardable
     delegate [
       :[],
-      :cleaners,
-      :cleaners=,
       :strategy=,
       :orm=,
       :start,
@@ -20,10 +18,9 @@ module DatabaseCleaner
 
     attr_accessor :allow_remote_database_url, :allow_production, :url_whitelist
 
-    private
-
-    def configuration
-      @configuration ||= Configuration.new
+    def cleaners
+      @cleaners ||= Cleaners.new
     end
+    attr_writer :cleaners
   end
 end