added 'ASSERT_THROW_ON_METHOD', 'ASSERT_NO_THROW_ON_METHOD', 'EXPECT_THROW_ON_METHOD', and 'EXPECT_NO_THROW_ON_METHOD' in base/assertion.coffee
fixed 'AllowedValueValidator.validate' in webapp/validator.coffee
fixed 'NullValueValidator.validate' in webapp/validator.coffee
updated testcase example