update cache on editing items

pandora/item/models.py

@@ -294,6 +294,7 @@ class Item(models.Model):
                     self.data[key] = data[key]
                 else:
                     self.data[key] = ox.escape_html(data[key])
+        self.cache = self.json()
         p = self.save()
         if not settings.USE_IMDB and list(filter(lambda k: k in self.poster_keys, data)):
             if is_task: