Remove duplicated method.

CHANGELOG.rdoc

@@ -13,6 +13,7 @@
   * E-mails now use any template available in the filesystem. Easy to create multipart e-mails.
   * E-mails asks headers_for in the model to set the proper headers.
   * Allow to specify haml in devise_views.
+  * Compatibility with Datamapper and Mongoid.
 
 * bug fix
   * Do not use lock! on lockable since it's part of ActiveRecord API.

lib/devise/models/authenticatable.rb

@@ -50,12 +50,6 @@ module Devise
         password_digest(incoming_password) == self.encrypted_password
       end
 
-      # Verifies whether an +incoming_authentication_token+ (i.e. from single access URL)
-      # is the user authentication token.
-      def valid_authentication_token?(incoming_auth_token)
-        incoming_auth_token == self.authentication_token
-      end
-
       # Checks if a resource is valid upon authentication.
       def valid_for_authentication?(attributes)
         valid_password?(attributes[:password])