FIX: Fix HTTP 500 on registry API endpoint

mopidy_pummeluff/cards.py

@@ -75,6 +75,8 @@ class Card(object):
         except (KeyError, AssertionError):
             raise InvalidCardType('Card class for type "{}" does\'t exist.'.format(card_type))
 
+        return cls
+
     @classmethod
     def get_type(cls, card_class=None):
         '''

mopidy_pummeluff/web.py

@@ -79,7 +79,7 @@ class RegistryHandler(RequestHandler):
         '''
         cards = []
 
-        for uid, card in cards.Card.all().items():
+        for uid, card in Card.all().items():
             cards.append(card.dict)
 
         data = {