Adding ApplicationModel to the test helper.

The Active Record tests should now include inside of it an
ApplicationModel.

Author: wangjohn

activerecord/test/cases/helper.rb

@@ -9,6 +9,7 @@
 require 'cases/test_case'
 require 'active_support/dependencies'
 require 'active_support/logger'
+require 'models/application_model'
 
 require 'support/config'
 require 'support/connection'

activerecord/test/models/application_model.rb

@@ -0,0 +1,3 @@
+class ApplicationModel < ActiveRecord::Base
+  self.abstract_class = true
+end