Fix broken setup path names and use path names in warden

lib/devise/initializers/warden.rb

@@ -50,7 +50,7 @@ Warden::Strategies.add(:authenticable) do
       success!(resource)
     else
       store_location
-      redirect!("/#{@mapping.as}/sign_in", :unauthenticated => true)
+      redirect!("/#{@mapping.as}/#{@mapping.path_names[:sign_in]}", :unauthenticated => true)
     end
   end
 

lib/devise/mapping.rb

@@ -17,7 +17,7 @@ module Devise
       @klass = (options[:class_name] || name.to_s.classify).to_s
       @name  = (options[:singular] || name.to_s.singularize).to_sym
       @path_names = options[:path_names] || {}
-
+      setup_path_names
     end
 
     # Return modules for the mapping.