Use the correct app summary for webpay

mkt/purchase/tests/test_webpay.py

@@ -60,7 +60,7 @@ class TestPurchase(PurchaseTest):
         eq_(req['pricePoint'], self.price.pk)
         eq_(req['id'], make_ext_id(self.addon.pk))
         eq_(req['name'], unicode(self.addon.name))
-        eq_(req['description'], unicode(self.addon.description))
+        eq_(req['description'], unicode(self.addon.summary))
         eq_(req['postbackURL'],
             absolutify(reverse('webpay.postback')))
         eq_(req['chargebackURL'],

mkt/purchase/webpay.py

@@ -106,7 +106,7 @@ def prepare_pay(request, addon):
             'price_point': addon.premium.price.pk,
             'id': addon.pk,
             'app_name': unicode(addon.name),
-            'app_description': unicode(addon.description),
+            'app_description': unicode(addon.summary),
             'postback_url': absolutify(reverse('webpay.postback')),
             'chargeback_url': absolutify(reverse('webpay.chargeback')),
             'seller': addon.pk,